330 Agricultural Experiment Station, Ithaca, N. Y. 



abundance of a water wbicli may be on tbe surface of the pro- 

 tballiuni or on the soil, they do not form a mycelial tube directly. 

 A very short tube is formed and into this the protoplasm migrates 

 and causes the end of the short tube to swell out into an oval or 

 oblong vesicle or the vesicle may be separated from the conidium 

 by a constriction. This phase reminds one of the formation of the 

 zoospore vesicle in the species of Artotrogus. But the formation 

 of this tube and of the vesicle does not take place so rapidly as in 

 Artotrogus^ and the form of the vesicle is quite different and varies 

 considerably in form as well as in size, but the most marked differ- 

 ence is that there is a firmer covering which appears to be in the 

 nature of a well-defined wall around the protoplasmic vesicle, while 

 in Artotrogus there is only a protoplasmic membrane. Here the 

 analogy ceases for zoospores are not formed. This cell is a ger- 

 minal vesicle or proembryo, and from this proembryo arises the 

 slender tube which pierces the cell of the prothallium and permits 

 the parasite to enter. If the conidia are lying in an abundance of 

 water they will germinate and produce a tube five to ten times the 

 length of the diameter of the conidium. This I have several times 

 observed, but in no such case have I observed the germ tube to 

 enter a cell of the prothallium. Leitgeb states that in such cases 

 which came under his observation the conidium only developed a 

 short tube and then soon died. 



The conidia possess a prominent apiculus which in development 

 is directed toward and rests partly in the stalk of the sporangium. 

 The sporangium develops from some of the superficial cells of the 

 botryose body, but so far as I have examined from cells which are 

 larger than the usual external cells. The cell begins growth in an 

 upright position or away from the moisture and appears very much 

 like an ordinary vegetative thread which is produced when the 

 plant is immersed in water except that it is greater in diameter. 

 When 60// to 80/y in length the end becomes enlarged and the pro- 

 toplasm collects into the forming sporangium. While the spor- 

 angium is forming the protoplasm is more coarsel}" granular at the 

 base, while at the terminal portion it is more hyaline, giving the 

 appearance of quite large and rather numerous vacuoles. When 

 the spore is mature it is ejected with considerable force in much 

 the same manner as the spores of the Entomophthorse. 



The aerial development of the sporangia instead of aquatic is in 

 correspondence with the nonciliated condition of the conidia. One 



