ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 203 



author in th^ Juan Fernandez Islands, off the coast of Chile. The 

 plants were comparatively small, rarely exceeding 8 or 10 cm. in length. 

 The structure of the growing plant is described in detail. It is fila- 

 mentous, with a pseudoparenchymatous cortex, the filaments being 

 repeatedly branched, and sometimes ending in a hair of the Pheeosporean 

 type. Thus the structure is ectocarpoid, and essentially the same as 

 Chordariacete, although at maturity it resembles that of Fucus. The 

 " apical cell," so-called, is described and discussed fully, as the result 

 of an examination of numerous examples. No connexion with the other 

 cells was ever found ; its shape is quite peculiar ; its wall much thicker 

 than in all other cells. Though it generally occurs in the conceptacles 

 and is very persistent, the author has series of sections in which it is 

 lacking. He believes it to be a small epiphytic alga, possibly a Codioluni, 

 which is unable to penetrate the mature cortex, and thus starts by infest- 

 ing the meristematic region. It has been observed in almost mature 

 cortex tissue, and is generally found in old conceptacles as well. The 

 development of the conceptacle is described. SplacJmidium is acknow- 

 ledged as a unique type, and is regarded as representing a branch of the 

 Chordariacege, and not as alhed with either Laminariacege or Fucacese. 



E. S. G. 



EiFect of Unilateral Monochromatic Light and G-roup Orienta- 

 tion on the Polarity of G-erminating Fucus Spores. — A. M. Hurd 

 {Bot. Gaz., 1920, 70, 25-50, 2 figs.). The primary purpose of this 

 investigation was to determine whether all wave lengths of light, the 

 intensity factor being eliminated, are able to bring about this orienta- 

 tion and establish the polarity of the germinating spores of Fucus 

 inflatas. Subsidiary studies are (1) on the phenomenon here called 

 " group orientation," consisting in the orientation of the cleavage 

 plane and the establishment of the apical and basal ends of the dividing 

 spore by the direction of some other spore or group of spores in close 

 proximity ; and (2) on the phototropisms of the young rhizoids in 

 monochromatic lights of equal intensities. The author reviews briefly 

 the literature on biological experiments with monochromatic light, 

 describes her apparatus and methods, and deals with polarity, photo- 

 tropism, and group orientation. After a short discussion she summarizes 

 her results as follows : (1) A convenient method for obtaining mono- 

 chromatic lights of equal intensity is the use of the thermopile and 

 galvanometer to obtain the relative intensity of the light transmitted 

 by accurate colour screens, and the adjustment of the distances of these 

 screens from the light source such that the deflections of the indicator 

 on the galvanometer scale are equal for each exposure of the thermopile 

 screened by the light filters in turn. (2) The effective wave lengths in 

 the establishment of the polarity of Fucus spores, the result of whose 

 use for unilateral illumination is the same as that produced by white 

 light (the orientation of the first cleavage plane perpendicular to the 

 direction of the incident light with the cell on the darker side of the 

 spore becoming the rhizoidal cell), are, with the intensity of strong 

 diffused daylight, the shorte^' rays of the blue end of the spectrum of 

 approximately 4000-5600 Angstrom units. There is some evidence- 

 that ultra-violet light can produce the same effect. (3) The nes:ative 



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