ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 463 



purposes, and that in the plants studied the absorption of gases is per- 

 formed by the superficial cells alone. Experiment proved that there is 

 little or no movement of water from below upwards. 



A number of brown seaweeds were examined without the presence of 

 starch being detected in any one of them ; proteids, on the other hand, are 

 present in considerable quantities ; the presence of the phycophtein 

 which distinguishes the assimilating organs of the Fucaceaa from those 

 of ordinary green plants may be directly or indirectly responsible for 

 their peculiar action. With the presence of a large quantity of proteid 

 material we may correlate the sieve-tube-like character of the rows of 

 component cells. 



Chemico-physiological Study of Algae.* — Herren O. Loew and 

 T. Bokorny state that algaa (Zygnemaceae), superficially dried with 

 blotting-paper, contain 85-90 per cent, of water ; when dried at 100° 

 their composition is — oil 6-9 per cent., albumin 28-32 per cent., cellu- 

 lose and starch 60-66 per cent. The oil is situated chiefly in the 

 chlorophyll region, but is not visible in drops under ordinary circum- 

 stances ; lecithin is probably present. The quantity of starch varies 

 very considerably according to circumstances ; during conjugation its 

 amount decreases, and glucose is formed. The gum is situated in the 

 cell-wall, the tannin, however, in the substance of the plant. Cbolesterin 

 and succinic acid (0*4 per cent.) are also found in algae, but the xan- 

 thines, leucine, and asparagine are not present. The authors conclude 

 that Baeyer's theory of the formation of starch is the correct one, not 

 only from the result of their own experiments, but because it is supported 

 by other facts, especially by the rapid growth of bacteria in solutions 

 containing compounds of metbyl. 



Crystalloids in Marine Algse.f — Herr J. H. Wakker has examined 

 the crystalloids in certain Florideae, Gracilaria dura, Dasya Wurdemanni, 

 and Bornetia secundiflora ; also in Vidalia volubilis, Derbesia Lamourouxii, 

 and four species of Codium. 



They are all unchanged by alcohol and water, with the exception of 

 those of Vidalia, which are dissolved in both these media ; they swell 

 up and subsequently disappear in dilute sulphuric acid or potash-lye. 

 The author was unable to find any crystalloids in living plants of 

 Dasycladus, Acetdbularia, and Bryopsis. 



The crystalloids in Laurencia, Sphserococcus, Bhizopliyllis, and Ploca- 

 mium are nearly globular strongly refringent bodies. Those of Laurencia 

 are gradually made granular by distilled water, alcohol, and dilute 

 potash-lye ; under the influence of concentrated sulphuric acid they 

 shrivel up, and exude small oily drops, in consequence of which the 

 author includes them under the category of " elaioplasts." 



Incrustation of the Cell- wall of Acetabularia4 — According to 

 Dr. H. Leitgeb, the incrustation of Acelabularia does not consist, as has 

 been usually supposed, entirely of calcium carbonate, but partly also of 

 calcium oxalate in a crystalline condition. This latter salt is found 

 chiefly in the inner layers of the cell- wall ; and is formed earlier than 

 the calcium carbonate. The sphsero-crystals of Acetabularia have been 



* Journ. Prukt. Chem., xxxvi. pp. 272-91. See Journ. Chein. Soc. Lond., 1888, 

 Abstr., p. 315. 



t Nederl. kruidk. Axon., iv. (1887) pp. 369-82. 



X SB. K. Akad. Wiss. Wien, xcvi. (1888) pp. 13-37. 



