- 169 — 



The deep colour given by acetic aniline blue seems to imply 

 that there is callose in the bristles [Strasburger 1902 pag. 216, 596]. 

 It seems also to agree with this that corallin does colour but 

 certainly not deeply. On the other hand pectin substances seem 

 not to be present, as the particular pectin dyes viz. ruthenium red, 

 vesuvin and safranin give no distinct colouring. 



The curious effect of tannic acid on various stainings viz. with 

 vesuvin, methyl violet and ruthenium red makes it likely that 

 lime giving substances make an essential part of the bristles [Klebs 

 1886 pag. 363]. 



The following observation points in the same way. When pro- 

 ducing cilia-staining preparations it is of importance that the mat- 

 ter spread over the cover glass is not heated to help the desicca- 

 tion, while otherwise the bristles will disappear. I think the cause 

 is that the lime giving substances are dissolved by the hot water, 

 and then naturally the staining cannot succeed where the effect of 

 the tannic acid bears the principal part. 



Scenedesmus quadricauda (Turp.) Bréb. Fig. 3, 4 [Ghodat 1902 

 pag. 213]. This very variable species I have often found with 

 beautiful bristles; this 

 is especially the fact 

 with forma typicus 

 Kirchn., and f. abun- 

 dans, Kirchn., but also 

 with more forms with 

 2, 4 or 8 cells in the 

 coenobium. 



In the cilia-stai- 

 ning preparations 

 looks at first sight as 

 if the bristles were 

 fixed in a rather irre- 

 gular way on the whole surface of the coenobium, but with dark- 

 ground illumination and with tannin vesuvin staining or the like, 

 it appears that the bristles are placed in tufts projecting from a 

 little knob of a very particular nature. The tufts are in general, 

 but there are many exceptions, placed in the following way. 

 1) There is commonly a tuft at all the points of the cells. The 

 tufts at the end-cells are generally fixed at the base of the spine 

 on the side turned inwards. 2) On the end-cells there are more- 



j-j- Fig. 3. Scenedesmus quadricauda (Turp.) Bréb. f. typicus Kirchn. 

 Stained with tannic acid vesuvin. Reichert Homog. Imm. V12, 

 Seibert Oc. I. 



Fig. 4. Scenedesmus quadricauda (Turp.) Bréb. f. abundans Kirchn. 

 Löfflers method (X 730). 



