Oct. 19, 1882] 



NATURE 



595 



as a punishment in Central Asia, the fact is that his 

 decoration with some 400 figures all over his body except 

 the soles of his feet, was evidently done by Burmese 

 tattooers, and is a masterpiece of their unpleasant craft. 

 There is an account of him by Mr. Franks in the Journal 

 of the Anthropological Institute for 1872. 



E. B. Tvlor 



PROF. STRASBURGER'S RECENT 

 RESEARCHES 

 Ueber den Bait nnd das Wachsthum der Zellhaute. Von 

 Dr. Ed. Strasburger, Professor an der Universitat 

 Bonn. (Jena, 1882.) 



THE work before us is another evidence of Prof. 

 Strasburger's untiring industry and minute research. 

 Interesting as all his books have been, this one may be 

 said to surpass its predecessors in this respect, inasmuch 

 as the questions with which it deals are of such fundamental 

 importance in botanical science. The main object of the 

 researches here published is to throw light upon two diffi- 

 cult and much-discussed points, namely, the intimate 

 structure of organised bodies, and the mode of growth of 

 cell-walls and starch-grains. With regard to the re- 

 searches themselves it need only be said that they appear 

 to have been carried out with Prof. Strasburger's accus- 

 tomed thoroughness and accuracy, and that they are 

 abundantly illustrated by beautiful drawings. The con- 

 clusions deduced from them are so remarkable that a brief 

 rhnme" will not be out of place. 



With regard to the intimate structure of organised 

 bodies, Prof. Strasburger entirely dissents from that view 

 which is known to all botanists as Naegeli's micellar 

 hypothesis. 1 This hypothesis was based upon the pheno- 

 mena of " swelling-up " which are so characteristic of 

 organised bodies, and upon the optical properties which 

 certain of these bodies possess. Prof. Strasburger points 

 out that swelling-up may be as well ascribed to the 

 taking-up of water between the molecules of the body as 

 to its being taken up between Naegeli's micellae. He 

 shows also in a striking manner that the double refraction 

 of organised bodies, such as cell-walls and starch-grains, 

 depends upon their organisation as a whole, for when 

 once their organisation is destroyed their double refrac- 

 tion is lost, a result which cannot be explained on the 

 micellar theory since the particles of the disintegrated 

 micella; would, like particles of broken crystals, still 

 retain their double refraction. According to Prof. Stras- 

 burger the molecules of an organised body are not aggre- 

 gated into micellae which are held together by attraction, 

 but they are linked together, probably by means of multi- 

 valent atoms, by chemical affinity in a reticulate manner. 

 Swelling-up is then the expression of the taking-up of 

 water into the meshes of the molecular reticulum, where 

 it is retained by intermolecular capillarity. The more 

 extensible the reticulum, that is, the more mobile the 

 groups of molecules within their position of equilibrium, 

 the greater the amount of swelling-up. The limit is 

 reached when the chemical affinity of the molecules and 

 the force of the intermolecular capillarity are equal ; if 

 the latter exceed the former at any moment the result is 

 the destruction of the molecular reticulum, or, in other 

 words, of the organisation. Protoplasm differs from 



1 Set Nature, vol. xxiii. p. 78. 



other organised bodies in that the grouping of its mole- 

 cules is undergoing perpetual change, the result of this 

 molecular activity being the phenomena which we term 

 vital. 



The growth in thickness of cell-walls and of starch- 

 grains takes place, according to Prof. Strasburger, by the 

 deposition of successive layers. Here again he is at issue 

 with Naegeli, who believed that the mode of growth was 

 intussusceptive with subsequent differentiation of layers. 

 It is impossible to go into detail with regard to the obser- 

 vations from which his conclusion has been formed ; it 

 need only be said that they are very numerous and 

 elaborate, and that they confirm those of Dippel and of 

 Schimper. Prof. Strasburger goes indeed so far as to 

 say that even the surface-growth of cell-walls is not intus- 

 susceptive, but is merely due to stretching. It must be 

 admitted that, assuming that all cellulose is derived from 

 proteid, it is difficult to understand how proteid particles 

 can be intercalated into the cell-wall to become subse- 

 quently converted into cellulose, but it is equally difficult 

 to imagine that the wall of large cells, such for instance 

 as an internodal cell of Nitella or a laticiferous cell of 

 Euphorbia, is simply the much-stretched wall of the 

 small cell from which these originated. Surely the 

 amount of solid substance in the wall of such cells as 

 these increases with its increased surface ! Here further 

 investigation is doubtless needed. 



There is, however, one point of detail which is of such 

 general interest that it deserves some consideration ; it 

 is with reference to the mode of formation of the cell- 

 wall and of the thickening-layers. Schmitz some years 

 ago expressed the opinion that the cell-wall is formed 

 by the actual conversion of a layer of the protoplasm, 

 that is, chemically speaking, by the production of a layer 

 of cellulose from a layer of proteid. With this opinion 

 Professor Strasburger entirely agrees, and he supports 

 it by a number of remarkable observations. When a 

 mass of protoplasm is about to clothe itself with a 

 membrane, the peripheral layer becomes densely filled 

 with minute proteid bodies, the microsomata, and 

 this layer then becomes converted into cellulose. The 

 wall of a young wood-cell of Pinus, for instance, is 

 clothed internally with a layer of protoplasm filled with 

 microsomata, which are arranged in spiral rows ; the 

 microsomata then gradually disappear, and the layer of 

 protoplasm is found to be replaced by a layer of cellulose. 

 which presents spiral striation corresponding to the pre- 

 viously existing rows of microsomata, and which consti- 

 tutes a thickening layer of the cell-wall. In cells the 

 walls of which become much thickened, the whole of the 

 protoplasm may be gradually used up in this way. 

 Again, the wall of pollen-grains and of spores is formed 

 from a peripheral layer of the protoplasm which contains 

 abundant microsomata. Its subsequent growth, and 

 especially the development of the asperities which it 

 commonly presents, is effected by the surrounding proto- 

 plasm which is derived from the disorganised tapetal 

 cells ; this is especially well shown in the development of 

 the epispore (perinium) of Equisetum and of Marsilia. 

 When an intine or endospore is present, it is produced, 

 like the outer coat, from a peripheral layer of the pro- 

 toplasm of the pollen-grain or spore. Further, the 

 septum which is formed in the division of a cell is 



