78 THE NATUEAL HISTOET EEVIEW. 



" tetraspores and cystocarps occur upon tlie same plant, as has been 

 " seen by the MM. Crouan in a species of Callithamnion; antheridia 

 *' and cystocarps have been seen by Bornet upon Lejolisia ; and 

 " antheridia and cystocarps have also been seen by myself upon 

 " Callithamnion hipinnatum, Crouan, and Herpothamnion hermaphrodi- 

 *' turn, Nageli. These observations point to the fact that the Elorideae 

 " are normally disecious, and that the plants with cystocarps may 

 " really be male and female individuals, in which, for the support of 

 ''■ the neutral organ, the formation of the sexual organs (antheridia 

 " and tetraspores) has been suppressed. 



" If my opinion as to the nature of the cystocarps is correct, 

 " they might possibly be wanting in certain Elorideae, whilst the tetra- 

 " spores must occur in all. It might be objected that there are 

 *' probably more Floridese, iii which the tetraspores are unknown than 

 " in w^hieh the cystocarps are unknown. This, however, is not con- 

 " elusive, inasmuch as the former are usually invisible to the naked 

 " eye, whilst the latter are easily seen and collected. There are some 

 " Ceramiaceae very generally distributed, and occurring in places 

 "where indefatigable algologists reside, in which tetraspores have 

 " been found, but no cystocarps have yet been observed, e.g. i2^oc?ocAor- 

 " ton Bothii and R. florididum and AntitJiamnion cruciaitim.'^ 



The result at which Professor Nageli arrives is that the cystocarps 

 ought not, in the classification of the Ceramiacese, to be used even for 

 subordinate divisions ; and if he is right in his views they must be 

 considered as asexual organs of very little importance. Whether 

 botanists wdll accept this conclusion time alone can show. At pre- 

 sent we can only say, as M. Vaillant has remarked in his recent work,* 

 that the notions of botanists as to the Florideae are very unde- 

 fined, and that although the nature of their organs may lead to the 

 supposition of sexuality, further observations are indispensable before 

 the existence of male and female Tlorideae can be looked upon as any- 

 thing more than a vague supposition. 



We must not close this report without referring to the disputed 

 question as to the nature of the conjugation which takes place in the 

 Zygnemaceae and other allied Algae. As far as w^e are aware it is not 

 yet settled whether this conjugation is a sexual process. We cannot 

 here discuss the point, and must refer those who are interested in 

 the question to Dr. De Bary's Essay, " UntersuchuDgen iiber die 



53. 



