DAi\rPING OFF FUNGUS AND ALLIED FORMS. 235 



The nuclei of Saprolegnia are very small (l-lj f^), vascular, for 

 "the most part oval, and have a well marked nucleolus. They are 

 usually so enveloped by granular protoplasm that their observation 

 is a very difficult matter ; this is especiallj' true in the sporangia. 

 The ordinary dift'ereutial stains seem wholly inadequate to demon- 

 strate them. The following treatment was the only one by wliieh 

 satisfactory results were secured. (1.) Fix with corrosive sub- 

 limate (satd. aq. sol.). (2.) Grade to 90% alcohol. (3.) Stain 

 thirty minutes in dilute alcoholic solution of iudulin (nigrosin), 

 and rinse in 70% alcohol. (4.) Stain in Grenacher's alcoholic 

 borax-carmine twelve hours or more. (5.) Mount in glycerine 

 and acetic acid, or gWcerine and alcohol. 



This treatment very well differentiates the nuclei in the hyphne 

 iiud in the earlier stages of the oogonia. In the mycelium of the 

 plant the protoplasm is arranged in a peripheral C3'linder, from the 

 inner surface of which extend projections into and across the central 

 vascular region, forming a rather complicated net-work. 



The nuclei are situated, for the most part, in these projections 

 and at the crossings or enlargements of the protoplasmic strands. 

 fFig. 7.] In the young oogonium, one readily sees the persistence 

 of the same general arrangement after the septum has been formed, 

 the nuclei being clustered along the inner border of the dense pro- 

 toplasmic investment. [Fig. -S.] In no case was I able to see 

 their migration into the, central vacuolar region, to the position 

 -occupied by the vacuoles with which Hartog considers them identi- 

 cal. This alone is not conclusive ; but taken with the observations 

 of Dangeard (Le Botaniste, April, 1890), with which my own 

 accord in some degi'ee, there seems to be ground for serious doubt 

 •concerning the accuracy of Hartog's interpretation. The nuclei 

 are much smaller than the vacuoles are when the}^ first appear, and 

 are considerably more numerous. Dangeard further claims to have 

 secured nuclei and vacuoles in the same preparation with sufficient 

 clearness to preclude belief in their identit}^ In addition to this it 

 must be noted that Hartog's idea, that the nuclei unite two by two 

 to form the so-called vacuoles, which in turn unite until all the 

 iiucleine is contained in from two to four masses, which resolve and 

 reunite to finally distribute nucleine to each of the oospheres, is 

 thoroughly at variance with what is known of the behavior of 

 nuclei in general. Aside from the union of male and female pro- 



