1907] CURRENT LITERATURE 



315 



Regeneration and polarity. — In a paper which has escaped our attention 

 until now (on account of the removal of Dr. McCallum to Arizona), Vochting" 

 takes up again these problems, stimulated by Klebs's report^' of the surprising 

 ease with which he was able to reverse the polarity of certain willows — the unat- 

 tained goal of many a previous experimenter. Much of this paper is devoted to 

 a reexamination of Klebs's work, which Vochting is unable to confirm and 

 against whose conclusions he enters vigorous protest. He finds no evidence that 

 polarity has ever been reversed by any experimental condition; he still holds that 

 it is a special property of the body, founded in the very structure of the egg, and 

 that it is not induced (as Pfeffer thinks) by any external agent. This conclusion 

 seems to be inevitable, when one observes the extremely different jx)sitions and 

 conditions under which eggs develop into embryos. In regeneration the various 

 natural or experimental conditions produce each an appropriate effect, according 

 as they cooperate with or oppose or do not affect polarity. In a supplementary 

 note, Vochting expresses his complete agreement with the conclusions reached 



by McCallum. '3 



Miss KuppER also attacks the problems of regeneration/** and after reporting 



pol 



disposition 



power 



eration is dependent upon an adequate supply of food. 



Not satisfied because various theories of regeneration fail to account for the 

 formation of one or another kind of organ ''when each of the conditions previously 

 ssigned as the causes of regeneration has been fulfilled/' she proposes a modifi- 

 cation of the Stojj und Form theory, postulating the existence of localized root- 

 forming and shoot-forming enzymes. To this the same objections apply as to 

 the older form of this theory; but the author has vague hopes that it may be cap- 

 able of experimental test, though "no results ready for publication have as yet 

 been obtained/' One neglected assumption (also made by Goebel) needs 

 quite as thorough investigation as any, namely, that food will accumulate at any 

 point before growth begins. — C. R. B. 



Ultramicroscopic structure. — Gaidukov continues his studies with the ultra- 

 microscope, describing in a late paper^^ the appearances in starch grains, cell walls, 

 and protoplasm. 



After an introduction upon the principles involved in the various forms of the 



" Vochting, H., Ueber Regeneration und Polaritat bci hohem Pflanzen. Bot. 



Zeit, 641:101-148. pis, ^-y. 1906. 



12 Klebs, G. Willkurliche Entwicklungsanderungen bei Pflanzen 96 ff. Jena. 1903. 



W 



B., Regeneration in plants. Box. Gazette 40:97 241. 19^5- 

 »4 KUPFER, Elsie, Studies in plant regeneration. Mem. Torr. Bot. Club 12:195- 



241. figs. 13. 1907. 



li Gaidukov, N., Ultramikroskopische Untersuchungen der Starkekomer, Zcll- 



membranen, und Protoplasten, Ber. Deutsch. Bot. Gesells. 



