ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 37iJ 



shell wbite filaments of mycelium, which in their turn soon showed 

 fructification. When the egg was opened, some days afterwards, 

 a tolerably thick layer of mycelium was found adhering to the shell- 

 membrane. There was no trace of an embryo. Experiments with 

 sixty eggs having the same origin gave only three entirely free from 

 the cryptogamic vegetation. In several the embryo had begun to 

 develope, and had been destroyed in the couise of the first week. 

 There were also in all the eggs considerable masses of mycelium, 

 usually occupying certain points on the internal surface of the shell 

 membrane, but, in certain cases also, floating in the albumen or rami- 

 fying in the yolk. When this mycelium was produced in the region 

 of the air-chamber, the cavity was filled with fructifying green 

 mould. Tbe moulds were of several species (often co-existent), the 

 most frequent being Aspergillus. 



The author then considers the origin of these growths, and 

 whether they ought to be attributed to the germination of spores 

 adhering to the walls of the vessels used in incubation, or contained 

 in the air inside them ; to spores deposited on the shell dui-ing the 

 interval between laying and incubation ; or to spores enclosed in the 

 egg itself before the completion of its formation in the oviduct ? 



Numerous experiments have led M. Dareste to doubt the two 

 former explanations, he having heated tlie vessels which were to 

 contain the eggs to 120° C. in order to kill any spores, and at other 

 times used the spray of carbolated water ; the vegetation nevertheless 

 developed as abundantly as before. He therefore supposes that the 

 spores were enclosed in the egg at the time when the yoke becomes 

 covered in the oviduct with layers of albumen. 



As, however, the methods used to destroy the spores are open 

 to objection, he would not consider the latter to be the most probable 

 hypothesis, did not other experiments point to it. The eggs used 

 in the first experiments all came from the same locality (Seine-et- 

 Oise). A batch of eggs from the department of Vienne, however, 

 only had three infected eggs, and eight which were exempt. Eggs 

 from the departments of the Oise and the Eure were experimented 

 on at the same time as those from the Seine-et-Oise, and the latter, at 

 the expiration of twelve days, had five eggs infected out of six. On 

 the other hand, six eggs from the Eure had only two infected. The 

 seven eggs from the Oise were, on the contrary, perfectly intact. 

 This difference between eggs placed in absolutely identical conditions 

 can only be explained by the inclosure of the spores in the eggs, in 

 the oviduct, and before the formation of the shell. It shows also 

 that the cause which infects the eggs is essentially local. 



Gayon has demonstrated the mecbanism of this infection. He has 

 shown that the prolapsus of the oviduct, at the moment of coijula- 

 tion, places its mucous membrane in contact with that of the cloaca, 

 and also with that of the cloaca of the cock. The oviduct, in resuming 

 its original position, draws in with it the microbia and all the 

 foreign bodies which it may find in these cavities. These circum- 

 stances are similarly produced at the moment of laying. The 

 existence of foreign bodies in the interior of eggs has also often 



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