182 SCIENCE PROGRESS. 



of the animal body took place by means of bacteria. These 

 statements, which have been made by Tischutkin, Dubois 

 and others, are based, however, on an insufficient knowledge 

 of the conditions of life of those plants, as has been shown 

 in another place. On the other hand, it has lately been 

 proved that there is a systematic relationship existing in 

 the case of some chlorophyll Thallophytes, which are 

 destitute of chlorophyll. Kamienski first drew attention 

 to the fact that the roots of a plant which lives as a 

 saprophyte, Monotropa hypopitys, are so closely invested 

 by fungal hyphse that the nutriment is only absorbed by 

 means of this sheath. Since then there have been found 

 fungi either on or in the roots of all saprophytes, as also in a 

 number of plants (Cupuliferae, etc.), which were hitherto not 

 regarded as such. 1 



The part which the fungus plays, particularly in the 

 last-mentioned cases, is, in spite of all contrary assertions, 

 still doubtful, and we cannot yet affirm that the root-tubercles 

 of the Leguminosas and their bacteroids, which have been 

 so carefully studied within recent years, have been quite 

 satisfactorily explained. It seems clear that the formation 

 of the little tubercles occurs as a consequence of the 

 influence exercised by some bacterium, and that the 

 organisms subsequently assume the Involution form known 

 as "bacteroids," which are bodies rich in nitrogen, and 

 capable of being digested by the plant. 



A treatise by Stahl 2 awakened particular interest in 

 the means of protection of plants against the lower 

 animals, especially snails, which play an important part 

 in our own country as enemies of vegetation. Many plants 

 are protected from them, partly chemically and partly 

 mechanically, i.e., by the constituent parts of their tissue, 

 which render them unpalatable to snails (tannin, acids, 

 bitter substances, ethereal oils and oily bodies as in the 

 liver-wort, or by bristly hairs, calcareous or silica cell- 



1 Cf. the detailed account in Frank, Lehrbuch der Botanik. 



2 E. Stahl, cf. Pflanzen u. Schnecken, eine biologische Untersuchung 

 iiber die Schutzmittel der Pflanzen gegen Schneckenfrass, Jena, 1888. 



