^91 J Life History of Hydrastis Ca?iade?isis. 73 



may be remarked here, as has been done by the previous 

 writers, that the establishment of the diplanetism of Achlya 

 brings it much closer to Saprolegnia. Indeed the structural 

 differences between them become reduced to a single one; 

 namely, that while in Achlya the sporangia formed from a 

 filament arise after the first one by lateral outgrowth below 

 the basal walls of the previous ones, in Saprolegnia they 

 usually arise inside of the preceding ones by the upward growth 

 of the successive basal walls. But I have seen, in an unde- 

 termined species of Saprolegnia, the formation of secondary 

 sporangia after the Achlya type on a few filaments. There 

 remain to be noticed two physiological differences so closely 

 connected as to constitute, perhaps, a single phenomenon. 

 The first swarming period in Achlya is reduced to its lowest 

 terms, and at its close the zoospores become aggregated into 

 a hollow sphere at the mouth of the sporangium, in response 

 to an apparent mutual attraction which Hartog 1 has termed 

 adelphotaxy. Is this mutual attraction the cause of the short- 

 ness of the first swarming period ? 

 Amherst, Mass. 



A contribution to the life history of Hydrastis Canadensis. 



HOMER BOWERS. 



(WITH PLATE VIII.) 



About ten years ago while engaged in the cultivation of 

 various indigenous plants and the study of their germination 

 and growth some deviations were observed in the behavior of 

 Hydrastis Canadensis so at variance with the accepted view 

 of the life history, that a minute study of all its peculiari- 

 ties was begun and from that time to the present it has been 

 followed with the view of bringing the facts to the attention 

 of botanists. 



My attention was first drawn to the plant specially, on dis- 

 covering a stage in its growth concerning which no record ex- 

 ists. Afterwards when investigation disclosed that this un- 

 known stage embraces a feature anomalous in the growth of 

 plants, a great incentive for further research was added. 

 This at length brought to light two other important facts 



Annals of Botany, vol. ii, no. vi f p. 216. 



