894 



SCIENCE. 



[N. S. Vol. II. No. 52. 



cells of Ascidia as haviBg a beautiful reticular 

 structure. In 1873 Heitzmann described a re- 

 ticulum in living Amoebse, aud in the same year 

 Frommann saw networks in the living white 

 corpuscles of the crayfish. In 1876 Schwalbe 

 referred the fibrillar appearances of ganglion 

 cells and of nerve fibers to the presence of a re- 

 ticulum, and a year later Eimer brought the 

 longitudinal striation of ciliated cells into the 

 same group by observing the cross meshes con- 

 necting the fibrils. 



In 1880, Schmitz supported the universal 

 occurence of reticular structures amongst plants 

 while Frommann, four years later, found retic- 

 ular structures in all the protoplasmic objects 

 he examined. He regarded the network, how- 

 ever, not as constantly persisting, but as form- 

 ing and disappearing. Leydig also found a 

 reticulum everywhere ; even the surface of cells 

 was porous. He thought the reticulum was 

 only a supporting part and that the true living 

 substance was in the meshes of this frame-work. 

 Van Beneden referred the reticular appearances 

 to a trellis-work of fibrils in three dimensions 

 of space. Carnoy made many contributions to 

 the evidence for the existence of a network 

 structure in protoplasm while Flemming and 

 Schneider could perceive only the existence of 

 fibrils. 



While there was thus growing up a concep- 

 tion that protoplasm was not homogeneous, but 

 that it contained fibrils which might be united 

 to form a net, there were other views as to the 

 structure of protoplasm. One of the strangest 

 was that of Fayod, who, in 1890, from results 

 obtained by injecting vegetable cells with mer- 

 cury, concluded that protoplasm consists of long, 

 hollow, spirally twisted fibers that are usually 

 twisted to form the walls of hollow strings, 

 which are also twisted. Previously Kiinstler 

 maintained that spherules built up the cell as 

 the cell did the tissue ; each spherule had a 

 dense wall and fluid contents, that is, was a ve- 

 sicle. Much more general, however, was the 

 recognition of granules within the protoplasm. 

 Called microsomes by Hanstein in 1883, these 

 minute specks were sometimes regarded as no- 

 dal points in a network, and again as being ar- 

 ranged in rows to make the apparent fibrils 

 and reticulum. Bechamp in 1867 and Martin 



in 1882 thought the granules might be living 

 units, but Altmann becomes, fi-om 1886-90, the 

 chief exponent of the view that granules are 

 the chief active, living constituents of proto- 

 plasm. In fact, he even supposes that proto- 

 plasm may have arisen as a sort of zooglea mass 

 made by granules that at one time led a sepa- 

 rate existence, much as bacteria exist to-day! 



Although it cannot be denied that in some 

 places protoplasmic bodies appear quite homo- 

 geneous in spite of all attempts to analyze them 

 optically yet it is generally conceded at the 

 present day that protoplasm has a structure, 

 that it has fibrillar portions that may be made 

 up of granules or associated with granules, 

 and that in many cases these fibrils are con- 

 nected so as to present the appearance of a 

 fi'amework or network. 



There is, however, another view of the struc- 

 ture of living matter which denaands serious 

 consideration as advanced by a most able 

 worker in various fields of protozoan and meta- 

 zoan morphology. Professor O. Biitschli, of 

 Heidelberg, the well-known author of the com- 

 prehensive monograph on the Protozoa in 

 Bronn's Klassen und Ordnungen. 



As early as 1878 he advanced the opinion that 

 the observed reticular appearance of protoplasm 

 might be but the expression of an alveolar struc- 

 ture, that protoplasm has a ft'Oth-like structure. 

 This idea he now supports by an extensive 

 treatise and by several minor papers. In his 

 view, living protoplasm is composed of fluid, 

 or nearly fluid, vesicles filled with a fluid ; 

 more like an emulsion than like soapsuds. The 

 walls of the vesicles form a framework or series 

 of partitions that surround closed chambers. It 

 is the optical section of these walls that gives 

 the appearance of a network. The contents of 

 the chambers, or alveoli, are spherules of liquid 

 isolated from one another by the vesicle walls 

 or enveloping layers, as are the air bubbles in a 

 mass of froth by the pellicles of the bubbles. 



This conception of the structure of proto- 

 plasm may justly claim the dignity of a theory 

 of the structure of protoplasm, since it plausibly 

 explains many of the observed optical appear- 

 ances and also some of the activities of living 

 matter. If an artificial mass is made having 

 this froth-like structure it may present some of 



