BOOKS AND CURRENT LITERATURE 165 



as the state of our knowledge now permits, the physical conditions and 

 chemical processes in cytoplasm and nucleus of living cells. The vocabu- 

 lary of colloid and enzym chemistry is special; but though an unavoid- 

 able obstacle to the unaccustomed reader, it is greatly reduced by careful 

 definition. The quantity of mathematics also is moderated to the abso- 

 lutely indispensable, though to a good many kinds of botanists there may 

 still seem to be rather much. This book should serve a double purpose: 

 first of giving to botanists of other sorts a clear concise statement of the 

 aims and attainments of the chemical physiologists; and second of indi- 

 cating to that part of the general public which still does any solid reading 

 that biology, like chemistry and physics and by means of them, is trying 

 to become an exact science. — G. J. P. 



Germination of a Parasite. — Biological studies of holoparasites 

 reveal many interesting facts. Aeginetia indica 1 differs from other 

 known forms in several respects. Its seeds will not germinate in soil, 

 water, or in a moist chamber but do so readily when in contact with 

 the roots of a variety of vascular cryptogams, gymnosperms and angio- 

 sperms. The seedlings will develop, however, only on certain species 

 of monocotyledons. Orobanche and Lathraea, related genera, germinate 

 only in the presence of the proper host . The seeds of other phanerogamic 

 parasites (Cuscuta, Santalaceae, Rhinanthaceae and Loranthaceae), 

 germinate under the same conditions which are favorable for plants in 

 general. Kusano's experiments with seeds of Aeginetia, wrapped in 

 one or more folds of paper, give evidence that the root of the host must 

 excrete some diffusible substance which stimulates germination. He 

 was not, however, able to report the presence of any specific substance. 

 The etching of marble by the roots of seedlings has everywhere been used 

 as a classic proof of the excretion of acids. Czapek's recent experiments, 

 however, throw grave doubts upon the validity of this proof. In fact, 

 the whole field of investigation on root excretion leaves much to be 

 desired as yet. The "hair tendrils.'' morphologically trichomes and 

 functionally root hairs and tendrils, and their penetration between the 

 epidermal cells, which is admirably illustrated in the plates accompanying 

 the text, appear never to have been described in phanerogamic parasites. 

 — Frederick A. Wolf. 



x Kusano, S., Further Studies on Aeginetia indica. Beihefte z. Bot. Centralblat 

 24: 286-300, pi. XI-XII. 1909. 



