116 ANATOMY AND PHYSIOLOGY OF 



lias endured for lialf-aii-hoiir, or at most two hours, it comes to 

 rest, tlie outer coat covered with cilias, disappears veiy rapidly (by 

 deconiposition ?) and germination commences by the coat of the 

 spore growing out into a filament. 



Observ. — These observations first demonstrated the existence of cilise 

 in the Vegetable Kingdom. It may be distinctly seen in Vaucheria 

 that they do not belong to the cell-membrane (spore coat), but to a mem- 

 brane clotLing tills. What the corresponding condition is in the zoospores, 

 is as yet unexplained, since a membrane enveloping the whole spore has 

 not yet been observed in these. Perhaps this may arise solely from the 

 small size ol the spores and the tennity of their coating membrane, per- 

 haps, however, the coat only exists locally aronnd the beak and the points 

 of inbertion of tbe dim. Mettenins, indeed (^^£eUmgezur. Botanik,'' i. 34), 

 assures us that the cibse are in connexion with the contents of the spores, 

 but he has not offered sufficient evidence of this. When we compare these 

 motions with the ciliary phenomena of animal cells ,and with the motions 

 of the seminal filaments of the higher Cryptogamia, no doubt can remain 

 that the movements of the cilise are the cause and not the effect of the 

 movement of the spore, as l^Tageli {^^UnicellulaT Algm^^' 22) beheved; an 

 opinion against which V. Siebold has already declared. The action of 

 poisonous substances, such as alcohol, opium, and iodine, immediately 

 arrests the motion. 



It appears possible for the formation of zoospores to originate 

 from one single granule of chlorophyll, while in other cases, where 

 only one or few spores are developed in a cell, (e, g. JDrapamaU 

 dia, GhcBtophoTo), perhaps larger sections of the mass of chloro- 

 phyll, or even the primordial utricle, by becoming constricted into 

 separate segmenta, are the parts concerned in the formation of 

 the spores. The actual conversion into a spore is not accurately 

 known in its intimate processes, but must consist essentially in 

 the formation of a cellulose membrane around the chlorophyll 

 granules. It has already been remarked that in Vaucheria the 

 whole mass of chlorophyll of a cell becomes coated with a mem- 

 brane. Intermediate forms between these two extremes are met 

 with, thus Saulier {^^Ann, d. Sc. nat Sme. Ser/' vii. 157) found 

 in the genus Derbesia, very closely allied to Vaucheria, that 

 neither tlie entire mass of chlorophyll collected into one spore, nor 

 did its grains remain isolated, but separate groups, each com- 

 posed of hundreds of grains of chlorophyll, became gathered up 

 into globular masses, acquired a membranous coat and formed a 

 short beak and a circle of cilige upon the surface."* Unger ("im- 

 mosa/' 1848, 129) observed a perfectly analogous formation of 

 the spores of Achlya prolifera^ which^ according to Thuret (''Ann. 



* See further on this subject, Thuret, ^^Ann, des. Sc. nat. 3 JSerJ' torn, 

 xiv. and xvi. ; Cohn on Rcematococcus, Nova. Acta. vol. xxii., and on 

 Stephanospho&ra, ^' Armals of Nat HisV Oct. andlSTov. 1852. — A. Braun. 

 " fleh. die Verjwngung,'^ Leipzig 1851. The active zoospores have no 

 cellulose membrane when first set free. — A. H. 



