While the trichromatic theory makes clear some of the processes involved in how we see color, it does not explain all aspects of color vision. The opponent-process theory of color vision was developed by Ewald Hering, who noted that there are some color combinations that people simply never see. For example, while we often see greenish-blue or blueish-reds, we do not see reddish-green or yellowish-blue.
Spay and Neuter Average Costs. The average costs of a spay or neutering procedure is $100 or $ 150. However, the costs of the surgery may be anywhere between $50 and $500.The price may depend on several factors including: 1  The method used for the spaying; presently there are 2 methods employed: the traditional method using a scalpel and the laser beam procedure. The method used for the spaying; presently there are 2 methods employed: the traditional method using a scalpel and the laser beam procedure. 2  The laser neutering procedure is costlier than the traditional surgery. 3  The location of the clinic may also be a factor that influences the costs.
1 The cost of spaying, a more complicated surgery, usually ranges from about $50 to $175. 2  Some clinics and animal hospitals can charge up to $200-$300 or more, depending on the weight of the dog.3  The cost of both neutering and spaying vary greatly by geographic region, and even by veterinarian. But lower cost sometimes means an assembly-line approach is used, so the dog might not get as much attention or recovery time. 2  Spay/USA has a referral service for reduced cost spay and neuter clinics. 3  In rare cases, such as with programs that use veterinary students, spaying and neutering can be free.