400 Journal of Agricultural Research voi. xviii. no. s 



The artificial propagation and dissemination of such fungous diseases 

 in cases where they may be readily controlled is thus, evidently, a 

 matter of no slight importance; and the necessity for a complete and exact 

 knowledge of their development and life cycle in all cases is obvious. 



Among the entomogenous forms, of which our knowledge is incomplete, 

 Soros porella uvella is of especial interest, not only on account of its pecul- 

 iar characters, which appear to be quite unique, but because of its proba- 

 ble economic importance. It was first observed in Russia by 

 Krassilstschik (iiY in 1886, and at intervals subsequently received a 

 certain amount of attention from Russian investigators ; but so far as the 

 writer is aware it has never been recorded from other countries, despite 

 the fact that it probably is widely distributed and destructive. 



That it has not been more generally observed is without doubt due to 

 the fact that fruiting bodies are not, as a rule, produced on the outside of 

 the insects which are parasitized and that the insects disintegrate soon 

 after death, leaving little that can be recognized. 



It is evident from an examination of the scanty literature relating to 

 the morphology and development of Sorosporella uvella that the informa- 

 tion contained therein is very incomplete and often inaccurate, and that 

 little or nothing is known of many phases of its development, pathogenic- 

 ity, prevalence, range of hosts, etc. The object of the present paper, 

 therefore, is to give as complete an account as possible of the stages in the 

 life history of the fungus which have previously been neglected or in- 

 accurately described, as well as to consider certain hitherto unrecorded 

 phases, some of which are of considerable importance from the taxonomic, 

 pathogenic, and even economic point of view. 



It will be shown further that one type of blood corpuscles of cutworms 

 acts as phagocytes, in that they engulf and apparently attempt to destroy 

 the vegetative bodies of the fungus. So far as the writer is aware, the phe- 

 nomenon of phagocytosis in insects attacked by fungous diseases has been 

 observed by no one, with the possible exception of Metchnikoff (14), and 

 is of especial interest, therefore, in the present connection. 



The observations herewith recorded are based on studies of artificial 

 cultures of the organism, on inoculation experiments with living hosts, 

 and on a histological study of infected insects prior and subsequent to 

 death. 



HISTORICAL SUMMARY AND TAXONOMY 



So far as the writer has been able to determine, the first description of 

 the form under consideration is that of Krassilstschik ( j j) in Russia, who 

 in 1 886 discovered the organism within the larval body of the coleopterous 

 sugar-beet curculio, Cleonus punctiventris. He referred the fungus to 

 Tarichium, which, although it has been considered by some writers even 

 in recent years to be a valid genus of the Entomophthorales, is in reality 



1 Reference is made by number (italic) to " Literature cited," p. 43S-439." 



