700 NOTES 



5. The term " protoplasm " was introduced by Von Mohl (Uberdie Saftbewegung 

 im lniKTu der Zellen, B.Z. 1846, p. 73). The fundamental importance of the proto- 

 plasm as t he vehicle of the vital activity of the cell was recognised about t he same time 

 by Nageli (Zeitschr. f. wiss. Bot. herausgeg. v. Schleiden und Nageli, 3, 1846). 

 Briicke (Sitzb. Wien, 41, 1861) was the first to lay stress upon the complex structure 

 of the protoplast ; the term " organised," which Briicke used to emphasise this 

 complex character of the living substance, was by Nageli extended to purely physical 

 matters, such as the micellar structure of substances which are capable of swelling, 

 etc. (cf. Nageli and Schwendener : Das Mikroskop, 2nd ed. p. 532). Nageli accordingly 

 includes starch-grains and cell- walls in the category of " organised " substances, 

 whereas Briicke regards " organisation " of this sort as a property peculiar to living 

 protoplasm. 



Among later observers, Sachs and especially Pfeffer have upheld Briicke's theory 

 of the highly convplex structure of the protoplast (cf. Pfeffer : Abh. sachs. 

 Akad. 16, 1890 ; id. Studien zur Energetik der Pflanze, ibid. 18, 1892, p. 156 sqq.). 

 Hanstein (Das Protoplasma als Trager der pflanzlichen und thierischen Lebens- 

 verichtung, Heidelberg, 1880) takes up the same position. 



The numerous attempts that have been made to demonstrate a definite structure 

 in the living substance, may be grouped under two heads, according to the points of 

 view of the investigators. Some authors rely chiefly upon direct observation, and 

 lay much less stress upon theoretical considerations. This tendency is exemplified 

 by the attempts of Max Schultze, Plemming and others to discover fibrillar structure 

 in protoplasm ; similarly, Frommann and Heitzman on the zoological, and Schmitz 

 and Strasburger on the botanical side, claim to have recognised a reticulate structure 

 by direct observation. Biitschli, finally, concludes, after careful investigation, that 

 protoplasm in general possesses an alveolar or '"foamy" structure. In many 

 cases, on the other hand, a definite structure has been assigned to the living substance 

 on purely theoretical grounds, in order to render the phenomena of heredity, and the 

 vital activity of protoplasm generally, more comprehensible. An instance is afforded 

 by Nageli' s assumption that the solid " idioplasm " i.e. that portion of the proto- 

 plasm which acts as the vehicle of the heritable properties forms a continuous 

 reticulum extending throughout each individual cell and through all the living 

 regions of the plant-body. Some authors believe that the living substance is made 

 up of equivalent ultimate particles, which are the actual vehicles of vital activity. 

 The " plastidules " of Elsberg and Haeckel are still of the order of magnitude of 

 chemical molecules ; but Altmann's " granula," De Vries's " pangens," Weismann's 

 " biophores " and Wiesner's " plasomes " all represent very complex particles of 

 the living substance. Altmann and Wiesner have endeavoured to demonstrate the 

 existence of these ultimate particles by actual observation. As a matter of fact, 

 the so-called " granula " of Altmann include a variety of different objects, such as 

 protein-particles, oil-drops, pigment-granules, etc., which are preferably termed 

 " microsomes," a term which has no theoretical connotation so far as plant-cytology 

 is concerned. Most probably Wiesner's " plasomes," so far as they have been 

 identified, are also by no means all equivalent particles. 



All the attempts that have been made to resolve the living substance into a number 

 of equivalent " ultimate particles," " living particles," " living elements," and so 

 forth, are founded, consciously or unconsciously, on the assumption that every 

 protoplast is made up of exactly equivalent particles, just as the various organs 

 and tissues of animal and vegetable organisms are composed of homologous ele- 

 ments, or" cells ; while it is possible that there is an analogy of this sort between multi- 

 cellular organs and individual cells, there is no positive evidence in favour of such a 

 comparison. The ultimate particles of which the living substance is made up, may 

 equally well be of various kinds (as Pfeffer has already pointed out), just as the 



