428 MARCUS M. HARTOG. 



the protoplasm a network of lines, formed of fine granules, and 

 marking out the protoplasm into polygonal areas. These lines 

 broaden out, and become converted into clear bands, which 

 slowly swell up " like transitory cell plates. '^ This we may 

 term the first stage of preliminary division. 



The second or homogeneous stage consists essentially in 

 the almost instantaneous disappearance of the clear bands ; the 

 protoplasm becomes lighter and homogeneous; the central 

 vacuole or vacuoles disappear at the same time that the basal 

 septum, hitherto concave towards the sporange, now bulges in 

 and becomes convex, showing that the turgescence of the 

 sporange has diminished. This stage hardly lasts more than 

 half a minute, and passes on to the 



Third stage, that of the shifting vacuoles. The proto- 

 plasm loses its homogeneity owing to the appearance of a 

 number of minute vacuoles, some of which would seem to 

 occupy the centre of the meshes bounded by the network of 

 the first stage, others to lie along the lines bounding them. 

 These vacuoles come and go, fuse or disappear, and reappear. 

 This stage gradually passes into the next. 



Fourth stage of final division. Now, as the protoplasm 

 shrinks from the wall, leaving a clear space interpreted by 

 Biisgen and De Bary as a substance, new lines appear, 

 clearly marked and more numerous than in the preliminary 

 division. They are the optical expression of the planes 

 separating the zoospores, which now contract, round off, and 

 escape a little later. 



These are the facts as described by Biisgen and Ward, and 

 as accepted by De Bary, their master, in his great work on 

 Fungi. In the above summary I have alluded to the fact that 

 Biisgen regards the lines of the preliminaj-y division as rudi- 

 mentary cell plates. Ward explains them as nuclear plates. 

 Biisgen and De Bary seem to consider them to be the ultimate 

 source of the expulsive substance lining the sporangial wall in 

 the last stage, which, swelling in water, would determine the 

 expulsion of the zoospores : they deny the existence of the 

 flagella on the sporangial zoospore of Achlya as described by 



