George B. Wislocki 635 



growth, become hard, and shed the velvet in September, while in late De- 

 cember, or in January, the antlers are cast off.* 



Examination of the schedule for gonads and antlers (graph i) re\eals that 

 the antlers begin their annual renewal at a time when the testes and seminal 

 vesicles are most inactive; they become hard and the velvet is shed when the 

 testes and male accessories are rapidly enlarging, whereas the antlers are lost 

 when the reproductive organs have begun to decline. These observations sug- 

 gest that some nongonadal factor must be responsible for the initiation of 

 antler grow^th. Fortunately for our knowledge of the antler-gonad relationship, 

 numerous deer have been castrated at various times. Few records of these ex- 

 periments, however, have been kept, beyond in some instances the antlers 

 themselves, or pictures of them. The most extensive account of such experi- 

 ments has been written by John Dean Caton,'- a judge in Illinois who studied 

 the natural history of deer as a scientific avocation. He castrated numerous Vir- 

 ginia deer and elk. From his classical account of these experiments the fol- 

 lowing passages are excerpts. They illustrate with the utmost clarity how the 

 antlers become typically deformed following castration. 



"If a deer be castrated at any time after the antlers are so far matured that 

 their velvet may be removed without material injury, and while they still 

 firmly occtipy their seat, they will irivariably drop off within thirty days there- 

 after, though it may be months before the time that they would have been 

 shed in the course of nature. In this case, and also when the operation is per- 

 formed after the antlers are dropped naturally, in the spring following w'hen 

 the new antlers on the perfect buck commence their growth, the same growth 

 commences on the mutilated animal, and progresses to all external appearance 

 the same as on the perfect animal till they have attained nearly the same size 

 as those which were last cast off. If the buck be a young one with a spike 

 antler, this will be a spike also of nearly the same length. If an old buck with 

 five tines, these will be of nearly the same size as the former, with five tines 

 also. These, however, never perfect their growth and never lose their velvet; 

 but at the time the antlers on the perfect buck lose the velvet, those on the 

 mutilated bucks stop their growth, but a moderate circulation is kept up in 

 the velvet, which remains warm to the touch, and so they continue stationary 

 till the severe weather of winter freezes the antlers through down to or very 

 near the burr, when by the application of some accidental force they snap oft 

 within half an inch or an inch of the burr, depending on the size of the 

 antler. If w^e now examine the detached portion of an antler we shall see that 



* With variations of a montli or two, a similar calendar holds for the majority of deer in 

 the temperate zone north of the equator, the only marked exception being the European 

 roe deer (Capreolus capreolus). In this unusual species the antlers appear in January, and 

 the breeding season occurs in August (Bischoff;' Keibel,* Stieve"). With this odd calendar the 

 females combine the imique fcatiue among deer of displaying delayed implantation, namely, 

 a period of three to four months before implantation occurs during which the fertilized eggs 

 lie dormant in the uterus. Implanted, as in other deer, at the usual time (November), the 

 young are consequently also born at the usual time (May). 



