3 H CHARLES T. BRUES AND RUDOLPH W. GLASER. 



tive statement. Dr. O. F. Burger kindly examined some of our 

 cultures and has expressed the opinion that they probably repre- 

 sent a species of Dematium or a related genus. Such morpho- 

 logical characters as we have been able to make out agree well 

 with descriptions of this genus to which it may be tentatively re- 

 ferred. 



PHYSIOLOGICAL ROLE OF THE SYMBIONT. 



As stated at the outset, we have attempted to determine the 

 physiological behavior of the Pulvinaria symbiont in culture to 

 ascertain in what way it may affect the metabolism of the coccid. 



Contrary to what occurs in the case of most yeasts, this or- 

 ganism produced no gas in media made from any of the sugars in 

 which it was grown. This is quite what might be expected as 

 the coccid tissues are undoubtedly rich in sugars and any organ- 

 ism producing gas in the presence of such substances could not 

 be tolerated in the body of the coccid. 



On the other hand a diastatic ferment is produced in quite ap- 

 preciable quantities. Whether this bears any relation to the 

 metabolism of the coccid is not entirely clear. In the adipose 

 tissue and body liquids, starch is probably not present to any con- 

 siderable extent, although in the large quantities of plant sap in- 

 gested by the coccids there must be substances upon which this 

 ferment might act. It has been shown also by Biisgen ('91) that 

 certain modifications are produced in the tissues of the food 

 plants of Coccids at the point where the mouth setfe are thrust 

 into the plant. These modifications appear to be induced by se- 

 cretions actually injected into the plant tissue by the insects and 

 they may act in liquefying or in partly digesting already liquid 

 or semi-liquid material, before it is withdrawn by the insect. It 

 is quite possible therefore that a diastatic ferment might act in 

 two possible ways in aiding the digestion of the coccid. If freed 

 in the blood, it might either pass into the alimentary tract, there 

 to act upon ingested food, or it might be taken up by the salivary 

 glands to be later injected into the plant and thus act as an extra- 

 intestinal digestive agent. Such extra-intestinal digestion is 

 known to occur in several diverse insects, although in these cases 

 the ferments are no doubt elaborated directly by the salivary 

 glands. 



