226 THE STRUCTURE OF CYSTOPUS CANDIDUS. 



branch on which it is formed. The sporangium is thus, from the 

 beginning, a muUi-nucleated cell. Each nucleus at a later stage 

 becomes the nucleus of a zoospore without undergoing further 

 division. The nuclei found in the club-shaped branches are 

 probably derived directly from the mycelium, no division-stages 

 having been observed in the sporangiophore itself It is possible, 

 however, that owing to the smallness of the nuclei the division- 

 stages are masked. 



The sexual organs, antheridia and oogonia, also contain 

 numerous nuclei. According to Fisch, the oogonium contains 

 from ten to twenty nuclei, the antheridium three or four. More 

 than this have been found in many cases. In the formation of 

 the oosphere, the protoplasm separates into periplasm and gono- 

 plasm, a cell-wall appears round the gonoplasm. A large number 

 of nuclei remain in the periplasm, but the gonoplasm does not 

 appear to possess nuclei at this stage ; at a later stage, however, 

 during the formation of the exospore, a number of nuclei make 

 their appearance in the oospore around a central oil-globule. 

 These observations do not agree with those of Fisch. According 

 to that observer, all the nuclei of the oogonium fuse together to 

 form the nucleus of the oosphere. According to Dangeard, the 

 central nucleus of Fisch is nothing more than an oil-globule, and, 

 so far as my observations go, I agree with him. Soon after the 

 separation of the oosphere a quantity of oil begins to accumulate 

 in or near the centre. This is stained deeply by hsematoxylin or 

 picro-nigrosin, and might easily be taken for a nucleus. Its oily 

 nature may be determined, according to Dangeard, by soaking 

 the sections for some time in chloroform, when it disappears, and 

 a vacuole is left. The oil-globule gradually increases in size, 

 until the exosporium is fully formed. It then takes up about 

 one-third of the diameter of the cavity of the oospore. 



The disappearance of the nuclei of the oosphere during the 

 earlier stages of its development, is probably only apparent, some 

 change taking place, of the nature of which we are not yet cogni- 

 sant. It is probable that these nuclei are included in the oosphere 

 at the time of its separation from the gonoplasm. 



The problem of fertilisation is an important one, but is difficult 

 to settle. At an early stage the antheridium contains numerous 



