referring now to fig1 through 3 in greater detail , there is shown a preferred form of rack member 2 which has an upper portion 4 , a lower portion 6 and a connecting portion 7 . as is shown in fig1 and 2 , the base portion , has two rows of separators 8 , 10 of generally identical size and shape with the separators of any one row being generally aligned with the other separators in said row in a longitudinal direction and each pair of adjacent separators 8 , 10 being aligned in a lateral direction . it will be appreciated that each pair of adjacent separators 8 cooperating with their aligned adjacent separators 10 defines a slot 12 . the width of slot 12 is so established as to permit ready insertion and removal of the slides while permitting generally firm retention of the slide within the slot 12 during processing . the lower portion 6 preferably has generally the shape of an upwardly open box defined by a pair of sidewalls 38 , 39 , and a pair of endwalls 13 , 15 . it is preferred that these walls 13 , 15 , 38 , 39 project upwardly farther than the upward extent of the separators 8 , 10 . the sidewalls 38 ( sidewall 38 has been omitted in fig2 for clarity of illustration of separators 8 ), 39 serve to resist undesired sliding movement of the slides out of the slots 12 . referring now to fig2 it will be noted that where the connection portion 7 merges into endwalls 13 , 15 there are provided generally inwardly projecting spacer elements 14 , 16 respectively . these serve to contact the slides in the end slots and resist undesired contact between the slide surface and the surface of connecting portion 7 . it is preferred that two or three spacer elements 14 , 16 be provided on each side at the same elevation , spaced from each other . it will be noted that as a result of positioning of separators 8 , 10 , generally inwardly from sidewalls 38 , 39 the slots 12 in the bottom portion are generally centrally positioned on portion 6 . referring now in greater detail to fig1 the slots provided in the upper portion 4 will be considered in greater detail . the upper portion has a series of peripheral walls including sidewalls 28 , 30 and endwalls 32 , 36 . a series of separator members 20 projecting generally inwardly from sidewall 28 define a series of slots 24 . similarly , a series of separators 22 projecting generally inwardly from sidewall 30 define a series of slots 26 . it will be appreciated that the slots 24 , 26 are not only aligned with each other , but also are aligned with slots 12 formed in base portion 6 . in this fashion , a slide such as slide 31 may be introduced into the slide rack by sliding action from above the rack causing the slide 31 to first have its opposed edges enter one slot 24 and one slot 26 and under guidance of these slots travel downwardly until its lower extremity enters slot 12 . referring still to fig1 it is noted that endwall 32 has a number of generally inwardly projected separators or spacers 34 which serve to resist undesired surface - to - surface contact between a slide in the adjacent slot and surface of endwall 32 . similarly , a number of inwardly projecting spaces 37 are provided on endwall 36 . it will be appreciated that by use of this rack member 2 slides may readily be introduced into secure positions where they are not contacting each other and are engaged solely at their upper and lower portions thereby not involving undesired contact on the emulsion - covered specimen - bearing sections . in a preferred embodiment of the invention , the slots 12 , 24 , 26 have a width of about 1 . 5 to 2 . 5 times the thickness of the slides the slots are adapted to receive so as to minimize the risk of damaging contact between the slides and separators 8 , 10 , 20 , 22 . the preferred slot width is about 2 times the slide thickness . it is preferred that the upper portion 4 have a height of about 8 to 13 mm and that the separators 20 , 22 be so spaced with respect to the base of slots 12 that when the slides are in place in the rack member 2 , the separators 20 , 22 will contact the frosted portions of the slides . the separators 20 , 22 preferably have a height of about 6 to 12 mm . lower separators 8 , 10 preferably have a height of about 2 to 4 mm . a generally u - shaped handle member 40 is provided in order to facilitate ready handling of the rack member 2 . in the form shown , the handle 40 has its opposed ends pivotally secured to pivots 42 , 44 which are disposed on opposed ends of upper portion 4 . the handle 40 provides a convenient means for engaging the rack member 2 for handling . while permitting movement to the position shown in fig2 for storage or insertion into a light box . the height of handle 40 measured from pivots 42 , 44 is greater than the spacing between the lower portion 6 , lower surface and pivots 42 , 44 . in a preferred embodiment of the invention it is contemplated that the rack member 2 may economically be made of a suitable material so as to be disposable . among the preferred materials are generally chemically inert plastic resins and protectively coated metals . it is specifically preferred that the material be relatively inert in the presence of hydrochloric acid , ethanol , methanol , xylene and acetone . referring now to fig4 there is shown schematically a form of slide adapted to be processed by the present invention . the slide 50 has an upper end 52 and a lower end 54 with a specimen 56 secured generally centrally on the slide . the upper portion of slide 50 has a frosted portion 58 . in placing the slide 50 in the rack member 2 , the lower end 54 will be received within a slot 12 and the frosted portion 58 will be secured within a slot 24 and a slot 26 . one conventional type of slide has a height of about 7 . 5 mm , a width of about 2 . 5 mm and a thickness of about 1 mm . the partition members 8 , 10 may preferably be of substantially uniform thickness . if desired , the upper extremities of partition members 8 , 10 may be tapered or otherwise of restricted thickness so as to function as pilot surfaces to assist with guiding of slides into slots 12 . such departures from uniform thickness shall for simplicity of disclosure herein be deemed to keep the partition of substantially uniform thickness . it is preferred that the elongated sidewalls of partition members 8 , 10 when viewed in elevation be substantially rectangular . referring to fig5 there is shown a preferred construction for an upper separator member 22 or 24 . as is shown , the separator member 22 is secured to peripheral wall 30 . this separator member 22 preferably has a substantially uniform thickness equal to the thickness of separators 20 , 8 and 10 . in the form illustrated , separator 22 does not have a generally rectangular side elevational configuration . it has an upper surface 60 which projects outwardly about three to five times the extent of the outward projection of lower surface 66 . it has a vertical surface 62 and a transitional surface 64 . with the bulk of the separator 20 , 22 , its upper extremity , maximum retention capability in respect of undesired slide movement is achieved while minimizing the likelihood of objectionable contact between the separator portions of the slide below the frosted section 58 . referring now to fig6 there is shown a form of reservoir means adapted for use in the present invention . it consists of a base portion 70 which is generally rectangular , and in the form shown , of substantially greater cross - sectional extent in plan than the overlying fluid reservoir 72 . this relationship minimizes the risk of undesired tipping of the fluid reservoir 72 . the fluid reservoir 72 is defined by walls 74 , 76 , 78 , 80 and is either formed integrally with base portion 70 or is secured in liquid - tight relationship thereto . overlying and preferably secured to fluid reservoir 72 is pilot portion 82 which is formed by walls 84 , 86 , 88 , 90 which converge downwardly toward the upper extremity of fluid reservoir 72 . it is noted that a pour spout 92 is integrally formed at the juncture of walls 84 , 90 . in a preferred practice of the invention , the slides are introduced into the various slots of the rack member 2 . after this introduction has been accomplished the user grasps the handle 40 and immerses the lower portion 6 and connecting portion 7 into fluid reservoir 72 which contains a bath of emulsion . the emulsion generally is coated on the slides up to the frosted portion . the rack member 2 is then lifted from the reservoir 72 and the emulsion - coated slides are permitted to dry at room temperature . it will be appreciated that the pilot portion 82 serves to facilitate introduction of the rack member 2 into the reservoir 72 and also serves to return to the reservoir emulsion which might drip off of the slides during withdrawal of the rack member 2 . finally , emulsion remaining in the reservoir 72 after processing may conveniently be restored to a storage container through pour spout 92 . fig7 illustrates a form of light - tight box which consists of a base portion 100 and a lid 106 . the box may advantageously be made of a black plastic material , but other suitable types of boxes may be used . a separator plate 102 containing a series of openings 104 is provided in the box . in use , the rack member 2 with the handle in the position shown in fig2 is placed in the base portion 100 on one side of separator plate 102 and a suitable dessicating agent such as caso 4 is positioned in the base portion on the other side of plate 102 . the openings 104 permit absorption of moisture by the dessicating agent and help further dry the slides during the exposure period . a suitable dessicating agent is that sold under the trade designation dri - rite . in order to improve the light - tight characteristics of the box it is preferred that the upper edge of base portion 100 contains an inwardly offset upwardly projecting flange 110 which cooperates with an outwardly offset downwardly projecting overlapping flange 108 of the lid 106 . if desired , tape or foil may be placed over the overlapping flange members 108 , 110 in order to provide further resistance to undesired entry of light into the box . in practicing the present invention with use of a light - tight container of that type shown in fig7 and 8 , the rack member 2 containing emulsion - bearing dried slides may be introduced into the box and the box closed . the box may be introduced into a refrigerated environment at about 4 ° c . the radioactive material which was incorporated within the specimen emits alpha particles , beta particles or gamma rays . this energy reduces the silver bromide ( agbr ) in the photographic emulsion to metallic silver . the refrigerated environment not only reduces undesired background on the slides , but also serves to resist distortion and shrinkage of the specimen . after this exposure for a predetermined period of time , the slides while retained in the rack are developed either by conventional autoradiography techniques or by gold - activated autoradiography . in the former process , red lights are generally employed , while in the latter developing is effected in complete darkness . after developing has been completed , the slides may be removed from the rack member . if it is desired to stain the slides , this may be done while the slides are in the rack before or after developing . it will be appreciated that by the method and apparatus of the present invention , the specimen - containing slides need merely be introduced into the rack member initially and the processes of emulsion coating , drying , storage in a light - free container , slide exposure , slide development and staining may all be accomplished without further individual handling of the slides . in addition , risk of damage to the slides through repeated handling in a darkroom is eliminated thereby producing improved quality of result in addition to improved efficiency of processing . further , if desired , staining may be accomplished while the slides are in the rack member . further , the rack member may be made of a material which makes it economical to dispose of after use . while for purposes of simplicity of disclosure , a specific preferred form of apparatus and method have been disclosed , it will be apparent that other forms may be provided . for example , a rack member adapted to hold more or less than the number of slides illustrated may be provided . also , should it be desired , the partition members on the base portion may be positioned immediately underlying the partition members on the upper portion or at an intermediate position . whereas particular embodiments of the invention have been described above for purposes of illustration , it will be evident to those skilled in the art that numerous variations of the details may be made without departing from the invention as defined in the appended claims .