190 KEPOKT— 1891. 



latter from the former. The first and simplest stage of cell- 

 genesis would be the Zooglce.a, where we find colonies of Sclii- 

 zomycetes embedded in a jellylike matrix secreted by them- 

 selves. A higher stage is represented by the non-nucleated 

 Cytodes and Plasmodia. In these the granules, according to 

 Altmann, correspond to the micro-organisms of the Zooglcea ; 

 but the colony has now the property of enclosing, acting 

 chemically on, and assimilating particles of foreign organic 

 matter — a power not possessed by the Zooglcea colony. 



The passage to nucleated Protozoa, Altmann supposes, 

 may be effected through the process of encystation which is 

 observable in some of the Cytodes. In these the protoplasmic 

 body developes an eiivelope, through pores in which protoplasm 

 passes outwards to form an outer layer, and this outer layer 

 may again develope an envelope. The nucleus may be sup- 

 posed to be developed from the central mass with its en- 

 velope, the cell-body from the outer layer of protoplasm. Thus 

 we have formed a nucleated Protozoan ; but this is still the 

 equivalent of a colony of micro-organisms, the individual ele- 

 ments in which are the granules. When the granules, as is 

 the case in many cells, are entirely separate from one another, 

 then we have a condition which is analogous to the Zooglcea ; 

 when, on the other hand, the granules are arranged end to end 

 so as to form fibrils, then the arrangement is more nearly ana- 

 logous with that of the colonies of ScJiizomycetes, in which the 

 individual elements are arranged in rows so as to form simple 

 or branching filaments. 



Transition-forms between the non-nucleated Cytodes and 

 Plasmodia and nucleated cells are to be looked for among the 

 Protista, in which there must be genetic stages in the forma- 

 tion of true nuclei. 



This correspondence between cells and colonies of micro- 

 organisms, Altmann is careful to state emphatically, is only a 

 phylogenetic one ; the granules of the cell-protoplasm are not 

 micro-organisms, and are incapable of being cultivated after 

 the manner of Bacteria outside the cell. 



The theory that the protoplasm-granules are the elements 

 in organic bodies, and that they correspond to micro-organisms, 

 is not new ; similar views have been put forward, among others, 

 by Henle and by Bennett ; but this conception has never before 

 been worked out with such thoroughness and supported by such 

 a series of careftd observations. Thus presented, the theory is 

 a very striking and suggestive one, and one the thorough dis- 

 cussion of which is very likely to lead to a more intimate know- 

 ledge of the constitution of organized bodies. 



Two papers which have been published simultaneously in 

 the last number of the " Quarterly Journal of Microscopical 



