Morphologie etc. — Physiologie. 85 



cytoplasm on opposite ends, respectively, of each of the pair of 

 spermatids. Gradually a definite granule or body is differentiated, 

 which develops as a thread or cord around the cell near to the plasma 

 membrane. This cord, the blepharoplast, stains homogeneously 

 throuijhout. Following its course the nucleus lengthens in close 

 contact with the blepharoplast, the two become indistinguishable by 

 the time one complete turn is made, and the body of the sperm, 

 which stains like chromatin, continues to increase in length until 

 the mature form is reached. Two cilia are developed, probably from 

 the forward end of the blepharoplast. 



No accessory bodies of any sort corresponding either to the 

 'Nobenkörper' of Ikeno or the 'limosphere' of Wilson are diffe- 

 rentiated. Agnes Arber (Cambridge). 



Blackman, F. F., The Plasmatic Membrane and its Orga- 

 nisation. (New Phytologist. XI. 5, 6. p. 180-195. 1912.) 



Four papers by Czapek (1910 — 11) on the plasmatic membrane 

 appeared concurrentl3'- with four papers by Lepeschkin (1910 — 11), 

 both observers approached the same subject from different points 

 of view. The author gives the chief results described in these eight 

 papers after a short Statement of the general principles of surface- 

 action and microchemistry. Czapek's first paper gives the details of 

 a study of the precipitates that can be produced inside the living 

 cell by certain agents of a basic nature e.g. •2''/o Solution of caffein; 

 he shews that practically all plant cells containing tannin give 

 this precipitate. 



His second paper is concerned with the injuring of the proto- 

 plasm by substances, which results in exosmosis of the contained 

 tannin; treatment with caffein then no longer gives the myelin- 

 formation. The exosmosis of the tannin is a convenient reaction for 

 testing the effect of various water-soluble substances on protopiasmic 

 permeability. 



The critical concentration to produce exosmosis was determined 

 in the case of the strenger acids, specific poisons and many organic 

 substances. 



The result of experiments on the correlation between surface 

 tension and exosmosis established a new principle of great funda- 

 mental importance, viz. "if any organic substance whatever is dis- 

 solved in water in sufficient amount to lower the surface-tension 

 to 0-68" (pure water = 1) "then this Solution just brings about ex- 

 osmosis from the cell", 



Czapek's third paper shews that the living cells of higher 

 plants have a surface tension of 0-ö8. The results of his researches 

 on the surface tension of colloids, give streng support to the lipoid 

 theory of the plasmatic membrane, for he shews that a streng 

 emulsion of a neutral fat in water has a minimal limit of about 

 068 for its surface tension. 



In the fourth paper the nature of the surface layer is discussed 

 in detail, and it is concluded that an emulsion containing a few 

 parts per cent of fat would give all the required properties. 



Blackman describes numerous experiments of Lepeschkin 

 dealing with the coagulation of the plasraa-membrane brought about 

 by different agents, such as heat, mechanical stress and chemicals, 

 and the light such action throws on the nature of the membrane is 

 considered. 



