382 CHAS. W. HARGITT. 



cell aggregates which are producing right along perfectly normal 

 and healthy polyps is to use a term whose significance implies 

 the very opposite. It is admitted in the above citation that the 

 tumor-like masses continued to live for a long time, as much as 

 sixty days according to a preceding sentence, which shows a 

 degree of vitality greater than that of colonies of the hydroid 

 when placed in the aquarium. This fact of itself should prompt 

 serious hesitation as to an assumption of a pathological condition. 

 It may throw some light upon the problem if attention is 

 directed to conditions involved in the life history of many of 

 these organisms. It is well known that many hydrozoa have 

 alternating periods of activity and repose — growth, reproduction, 

 etc., followed by corresponding periods of decline and more or 

 less degeneration. In some these periodic alternations are 

 correlated with seasonal changes in which temperature is an 

 important factor. In others it is directly correlated with repro- 

 ductive activities and has apparently little relation to season or 

 temperature. What is of immediate importance in this connection 

 is the fact of rather evident degenerative phases. For example, 

 it is well known that in the spring, following the active reproduc- 

 tive period in several species of Tubularia, there is a marked 

 degenerative phase, first evident in the casting off of the hy- 

 dranths of almost the entire colony, then the gradual disintegra- 

 tion of the whole trophosome, till within a period of a few weeks 

 it is difficult to find an entire and vigorous vegetative colony. 

 An examination of the histological condition of the degenerative 

 coenosarc reveals the fact of positive decline marked by cytolytic 

 conditions which might really be designated as pathologic for 

 the time being. But even here a continued study would probably 

 reveal the fact of its being associated with perfectly normal 

 cyclic phases of life, being in fact phases of varying physiological 

 states to which reference has already been made in an earlier 

 connection. Similar facts of degeneration phases have also 

 been described as associated with regenerative activity in hy- 

 droids. In experiments on Tubularia Stevens states in so many 

 words: "The red granules seen in the circulation of regenerating 

 pieces of Tubularia are derived from the disintegrating ento- 

 dermal ridges, and are ejected by the young hydranth soon after 



