36 Discussion 



Comfort: They would not have enough of them at any time to make a 

 significant experiment ; that is the difficulty. Assuming this goat figure 

 turns out not to be merely an accident of this particular population, 

 since this is a fairly small group, if we find the same in other goats it 

 might be even more interesting to see whether this is due to any differ- 

 ence, as Prof. Bourliere suggested, in their metabolic rates. And it 

 might be interesting to see whether it is in fact true that the more inbred 

 domestic goats decline at a greater rate. 



Landowne: With regard to Prof. Gillman's very interesting report on 

 the parasitism of lizards, we see many old people with extensive athero- 

 sclerosis and other disorders who live with their infirmities and disease. 

 Does this anaemia or this parasitic infestation account in the main for 

 the mortality of these animals ? These questions that seek beyond the 

 first line of evidence sometimes yield most discouraging results. But this, 

 to me at least, opens the pattern of investigation : you make the observa- 

 tion, you then look for the experiment. 



Gillman: As I mentioned, after Dr. Pienaar's initial findings (recently 

 reported fully in his Ph.D. thesis — and which were fascinating from a 

 number of points of view, including the types of anaemia which develop 

 in these animals), a reptilarium was started in the Medical School. Quite 

 a number of animals even bred in captivity. One variety of lizards, even 

 in captivity, frequently succumbed to heavy gregarine infections. One 

 of the biggest difficulties was to eliminate the apparently tick-like animal 

 which infested the group and which was shown to transmit this infection. 

 When the transmitter was eliminated the mortality rate of the young 

 and of the middle group of animals, of about 6 or 8 months of age, 

 decreased considerably. There did seem to be a definite relation, there- 

 fore, between infection with these blood parasites and mortality rates. 



Best: Have you a good supply of lizards that are free from this infec- 

 tion? 



Gillman : That I cannot say, unfortunately, because both my student 

 and I have left the Medical School in Johannesburg. However, Dr. 

 Pienaar has now been appointed to the position of game warden in one 

 of the South African game reserves, and one hopes to get some fascina- 

 ting information from him in the next few years. 



Lorge: I would like to underline these comments that have been made 

 about nutrition in another way : I have been interested in the supple- 

 mentation of animal feeds with antibiotics, and am raising the general 

 question "Whether any veterinarian (or any other related group) knows 

 what happens to animals fed antibiotics as a supplement to prevent 

 infection, as opposed to those given adequate quality and quantity of 

 vitamins and the like, in terms of longevity and other traits?" I have 

 seen no data, except that the group given antibiotic supplement is 

 subject to less disease and comes to full size at an earlier age. It seems 

 to me that here we have a series of interacting forces, not only caloric 

 content and vitamin content but also the possibility of throwing off 

 disease by a supplementation factor of some kind. 



Bourne: There is some evidence that some of the antibiotics have a 

 vitamin-like action. 



