THE DIAMOND-BACK TERRAPIN. 109 



among young terrapins hibernating the first year after birth is, however, very small. 

 There may be an increase during the year following, but it is negligible. The death rate 

 in the nursery house, however, is a matter of importance, though in certain years it is 

 small. The cause of heightened mortality in the winter-fed individuals is a disease, 

 rather cancerous in nature, which attacks the head, flippers, and especially the tail of 

 the terrapin. The disease rots off the tail and spreads to the body proper, probably 

 affecting the spinal cord and causing paralysis and death. Often terrapins become blind 

 or unable to eat because of the disease. Its cause is unknown, though it probably is 

 due to a microorganism. The disease seems most virulent to those nursery boxes which 

 are best heated or in the sun, while those which remain throughout the cold season in 

 the shade or at a considerably lower temperature than the others do not suffer so high 

 a death rate. The disease does not attack the weak and small terrapins alone, but 

 often kills some of the best grown. The kind of food used seems to have no connection 

 with the prevalence or the virulence of the disease. Antiseptic washes and thorough 

 cleanliness in the house and boxes apparently have some advantages, but the disease 

 will prevail even when the most scrupulous care is taken. Possible value of antiseptic 

 treatments seems to be borne out to some extent in the table on page 1 10. Treatments 

 have been with potassium permanganate solution applied to the nursery boxes at intervals 

 of a day or every few days. The solution is poured into the boxes and thrown upon the 

 sides, allowed to remain some time, and then drawn off. Early in the fall before young 

 terrapins are housed a thorough treatment with formalin or copper sulphate solution 

 is given the boxes and walls of the house. The floor, being sand, is treated with lime. 



The first year that any antiseptic was used in the nursery house was 19 15. In 

 1914 the percentage of mortality among terrapins housed for the winter was 29. In 

 1915, with the disinfecting treatments being used, the mortality dropped to 5 per cent. 

 However, this dropin mortality rate may have been due to causes other than the use of 

 the disinfectants, for since 1915 there has been a continued high mortality rate even 

 though disinfectants have been used regularly. 



Apparently the infecting organism can live in either salt, brackish, or fresh water, 

 as the disease, once started, spreads when the water in the nursery boxes is changed 

 from fresh to salt, or vice versa. Certain terrapins that are attacked recover after 

 several weeks, but the majority die. What possibly is another symptom of the same 

 disease, or perhaps another disease altogether, is the so-called "softening of the shell" 

 among the young terrapins. It is found among the terrapins that make no growth 

 and is due, perhaps, to faulty absorption of the yolk sac or to possible infection of the 

 body wall during this process. Such infection could be readily conveyed to the internal 

 organs and destroy the health of the terrapins so affected. The "softening of the 

 shell" symptom is always accompanied by loss of the power of growth and sometimes 

 by the loss of pigment in the carapace or by a deadened appearance of the entire shell. 

 Terrapins that develop this latter symptom rarely live. The offspring of the Texas 

 stock are as susceptible to the disease as those of the Carolina. Hybrids (Carolina- 

 Texas cross) are none the less susceptible to the disease. 



From a study of the winter-fed terrapins during the winter of 1919-20, it is sug- 

 gested that high temperature and direct sunlight on the nursery boxes in which are held 

 the several lots of yearlings are correlated closely with the prevalence of the disease. 

 It appears that the greatest mortality occurred in those boxes closest to the stove and 



