204 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



phototropism of the rhizoids in monochromatic light is also primarily a 

 function of the quality of the light, since, with equal intensity of 

 illumination, the wave lengths of the re(^ end of the spectrum are 

 without effect, while those of 4000-5200 Angstrom units produce the 

 same phototropism produced by white light. (4) The term " group 

 orientation " is suggested for the phenomenon of the orientation of the 

 first cleavage plane of a dividing spore with reference to the position of 

 adjacent spores, such that it is perpendicular to the direction of the 

 centre of a group or of a single spore within the effective radius, with 

 the subsequent development of the cell on the side towards the source 

 of stimulus as the rhizoidal cell. (5) This group orientation reported 

 ' in other species is a conspicuous phenomenon in every culture of Fums 

 inflatus, the stimulus acting in such orientations being so strong that 

 when spores are separated by as much as 0*2 mm., and often more, 

 light stimuli as a rule fail to overcome it. (6) The chemical stimulus, 

 which orients the direction of the first cleavage plane and determines 

 which cell shall become the rhizoidal cell in group orientations, has no 

 power to cause a chemotropism of the rhizoids. E. S. G-. 



Carbon Monoxide a Respiration Product of Nereocystis Luet- 

 keana.— S. C. Langdon and W. E. (tAiley {Bot. Gazette, 1920, 70, 

 230-1), figs, in text). The investigation was carried on during the 

 summer of 1918 at the Puget Sound Marine Station, Friday Harbour, 

 Washington. The authors give the following summary : (1) The 

 existence of a percentage of carbon monoxide in the gas contained in 

 the pneumatocyst of N. Luetkeana is confirmed. (2) The substance of 

 the kelp when ground and allowed to undergo autolysis and decay does 

 not form carbon monoxide by enzyme action or fermentation process. 

 (3) Kelp plants, in which the gas normally present within the float 

 (pneumatocyst) is replaced by air, form several per cent, of carbon 

 monoxide within a few days. (4) The formation of carbon monoxide 

 takes place only when oxygen is present as one of the gases within the 

 float. No carbon monoxide is formed when the float is filled with 

 nitrogen or hydrogen. (5) Light does not affect the rate of formation 

 of carbon monoxide. (6) The gas obtained from the cavities of various 

 other plants failed to show a similar occurrence of free carbon monoxide. 

 (7) The percentage of free carbon monoxide which occui's in the float 

 of N. Luetlceana is considered to be a respiration product for the 

 following reasons : It forms only when oxygen is present within the 

 float ; it forms as readily in the dark as in the light ; it is not formed 

 by enzyme or fermentation process when the substance of the plant 

 undergoes autolysis and decay ; and it is not formed in killed plants. 



E. S. Gr. 



Fungi. 



Note on certain Variations of the Sporocyst in a Species of 

 Saprolegnia. — Maejorie L Collins {Proc. Linn. Soc. iV, S. Wales, 

 1920, 45, 2, 277-84, 11 figs.). Considerable variation in the develop- 

 ment has been observed in artificial cultures of Saprolegnia, as first 

 described by Lechmere in the New Phytologist, 1910. M. Collins has 



