FUNGUS OCCURRING IN PULVINARIA INNUMERABILIS. 303 



Concerning the distribution of the symbionts in the body of 

 Ccroplastes, Berlese gives no account, except to state that they 

 generally occupy the visceral cavity completely in all individuals, 

 in numbers estimated at from 60,000-70,000 cells. 



Two other genera of soft scales, Kcnncs and Physokermes, 

 have been the subject of investigation by Sulc ('07) and Vejdovsky 

 ('07). The former found two distinct symbiotic organisms in 

 two species of these Coccids, readily distinguishable from one 

 another on the basis of size and form. These he described as 

 representatives of a new genus, Kerminicold. Vejdovsky re- 

 garded them as Saccharomycetes in which opinion Sulc con- 

 curred. The microscopical structure of the symbionts was care- 

 fully described and is similar to that of the species in Pulvinaria 

 studied by us, although Kcnninicola evidently has a much more 

 prominent and discrete nucleus and fewer multinucleate cells ; 

 also the form of the cells is generally much more elongate. 

 Vejdovsky found the symbionts in the fat cells of the host in 

 large numbers and observed them freed in the haemolymph as a 

 result of a disintegration of the adipocytes which he believed due 

 to the activity of the included organisms. He, therefore, re- 

 garded them as parasites, but pointed out that their activities do 

 not affect the gonads of the host, nor the development of the eggs 

 in its body. They do, however, serve to break down the fat and 

 to consume the remaining tissues of the host's body, after which it 

 remains a shell for the protection of the now fully developed 

 nymphal Kcrmes. 



In a later paper, Sulc ('10) gives a more extended account of 

 the similar organisms of a number of Homoptera and speculates 

 at considerable length upon the relations between the insects and 

 fungi. After more extended study, his ideas have been consider- 

 ably modified and he has come to regard the microorganisms as 

 essentially symbiotic in their association with their host insects. 

 He suggests that the production of enzymes by yeasts (for he 

 still refers the symbionts to the Saccharomycetes) must be con- 

 sidered in any interpretation of their physiological relations to the 

 insects. Apparently he made no attempts at cultivation in vitro. 



Pierantoni has considered the symbionts of certain Coccidze in 



