MICROSCOPIC STUDY OF THE CRYPTOGAMIA. 45 



dation. Thus the discovery was announced by M. Audouin in 

 1837, that the disease termed muscardine, which annually carried 

 off large numbers of the silkworms bred in the south of France, 

 really consists in the growth of a fungous vegetation in the interior 

 of their bodies, the further propagation of which may be almost 

 entirely prevented by appropriate means; in the succeeding 

 year, the fact was brought forward by several Microscopists, that 

 yeast also is composed of vegetable cells, which grow and multi- 

 ply during the process of fermentation ; and subsequent re- 

 searches have shown that the bodies of almost all animals, not 

 even excepting Man himself, are occasionally infested by Vege- 

 table as well as by animal Parasites, many of them remarkable 

 for their beauty of configuration, and others for the variety of 

 the forms they assume. The various parasites which attack our 

 cultivated plants, again, such as the " blights" of corn, the po- 

 tato fungus, and the vine fungus, have received a large measure 

 of attention from Microscopists, and much valuable information 

 has been collected in regard to them. It is still a question, how- 

 ever, which has to be decided upon other than microscopic evi- 

 dence, how far the attacks of these fungi are to be considered as 

 the causes of the diseases to which they stand related, or whether 

 their presence (as is undoubtedly the case in many parallel in- 

 stances) is the effect of the previously unhealthy condition of the 

 plants which they infest ; the general evidence appears to the 

 author to incline to the latter view. 



Of all the additions which our knowledge of the structure and 

 life-history of the higher types of Cryptogamic vegetation has 

 received, since the achromatic microscope has been brought to 

 bear upon them, there is none so remarkable as that which re- 

 lates to their Reproductive function. For the existence in that 

 group of anything at all corresponding to the sexual generation 

 of Flowering Plants, was scarcely admitted by any Botanists ; 

 and those few who did affirm it were unable to substantiate their 

 views by any satisfactory proof, and were (as the event has 

 shown) quite wrong as to the grounds on which they based them. 

 Various isolated facts, the true meaning of which was quite un- 

 recognized, had been discovered from time to time, such as the 

 existence of the moving filaments now termed "antherozoids," in 

 the " globules" of the Chara (first demonstrated by Mr. Varley in 

 1834), and in the " antheridia" of Mosses and Liverworts (as shown 

 by linger and Meyen in 1837), and the presence of " antheridia" 

 upon what had been always previously considered the embryo- 

 frond of the Ferns (first detected by Nageli in 1844) ; but of the 

 connection of these with the generative function, no valid evi- 

 dence could be produced, and the sexual reproduction of the 

 Cryptogamia was treated by many Botanists of the greatest 

 eminence, as a doctrine not less chimerical, than the doctrine 

 of the sexuality of Flowering Plants had appeared to be to 

 the opponents of Linnaeus. It was by the admirable researches 



