16.1 Haughivout and Korrilleno: Intestinal Parasites 53 
(F. G. H.) evidence is accumulating to show that immunity in 
man is, at least, not invariable. 
The physiology of Ascaris has been looked into by several in- 
vestigators, and much has been brought out that may be interest- 
ing in connection with the foregoing. Schwartz, (50) who has 
recently made an investigation into the nature of certain hsemo- 
toxic substances in Ascaris, has reviewed the work of some of 
the other investigators. Hall (26) quotes Garin as stating that 
the nematodes of the digestive tract live in all cases at the 
expense of the wall of the intestine and not on the food to be 
found in the lumen of the gut. Oxyuris and Ascaris, he says, 
live on epithelial cells, and Ancylostoma and Trichuris on blood. 
The nature of the attack on the tissues by hookworms, he states, 
is mechanical ; that of Trichuris is chemical. Crowell and Ham- 
mack cite the case of Albert and Mendoza (3) where a toxic 
action v/as attributed to Ascaris. They also cite Flury(l9) who 
experimented on Ascaris recovered from the intestine of the 
horse and the pig.® 
Flury succeeded in demonstrating volatile aldehydes of fatty 
acids; free valerianic, butyric, and other acids; alcohols and 
esters in the body substances and excretions of his ascarids. He 
was led to the belief that irritation of the intestinal mucosa 
and the nervous and other clinical symptoms of ascariasis could 
be attributed to these substances. 
Haughwout(27) cites Gibson who believes that Ascaris may 
produce an antivitamine or growth-inhibiting substance. He 
quotes Gibson as follows : 
The existence of an anti-vitamine or at least of growth inhibiting 
substances formed by ascarids is suggested by an observation which I 
made in connection with some milk feeding experiments with puppies. 
In a series of five young puppies fed on cows’ milk growth stopped in 
four of the animals when 44 days old. Following the administration of 
an efficient vermifuge, there resulted the passage of many ascarids from 
the four dogs in which growth had ceased. Growth was immediately 
reestablished. 
By kind permission of Professor Gibson and his collaboi'ator. 
Dr. Isabelo Concepcion, we reproduce the growth chart of the 
above-mentioned dogs (fig. 1). 
^Ascaris suum or A. suilla, of the pig, is morphologically indistin- 
guishable from A. lumbricoides of man, and these species are looked upon 
as identical by many helminthologists. 
