566 SUMMARY OF CURRENT RESEARCHES RELATING TO 



microscopic particles of mycoplasm, able to withstand high temperatures 

 and absence of oxygen, and able to build up proteins and carbohydrates 

 from inorganic materials, were incorporated by amoeboid non-nucleated 

 monrra. Others formed free bacteria, whence arose Cyanophyceae and 

 fungi. Some CyanophyceEe became symbiotic in nucleated cells, and 

 tli ns. by double symbiogenesis, arose the vegetable kingdom. But 

 t here is no evidence of Mereschkowsky's non-nucleated monera. M inchin 

 strongly supported the position that chromatin-elements represent the 

 primary organisms, and that cytoplasm is secondary. As every living 

 creature or microcosmic unit is marked by permanent specific individu- 

 ality (in spite of metabolism, adaptability, and variability) it is clearer 

 to speak of chromatinic elements, particles or units rather than of 

 chromatin-substance. 



The reasons for regarding the chromatinic elements as of primary 

 importance are : the preponderating physiological role of the nucleus ; 

 the individualization of the chromatin particles — almost as if they were 

 individuals ; and the " immortality " of the chromatinic particles in the 

 life-cycle of organisms generally. Particular individual chromosomes 

 can be tracked throughout a life-cycle. In many cases every cell of the 

 body has chromatinic elements from its two parents, and these maintain 

 their specific individuality unimpaired. The chromatinic particles are 

 the only constituents of the cell which maintain persistently and unin- 

 terruptedly their existence throughout the whole life-cycle of Hving 

 organisms universally. 



It is suggested, then, that the earliest living beings were minute, 

 possibly ultra-microscopic particles which were of the nature of chro- 

 matin. Their analogues may be looked for in the somewhat dubious 

 organisms called Chlamydozoa. They may be thought of as specks of 

 a substance like chromatin, multiplying by binary fission, producing 

 ferments, and building up protein molecules from the simplest inorganic 

 substances. Evolution may have proceeded along two main lines — 

 vegetative and predatory. On the latter line, the primitive organisms 

 gained an enveloping matrix of protoplasm — the periplasm, either around 

 each unit, or like a zooglcea. Thus arose the prototype of the animal, 

 with amoeboid movement, engulfing periplasmic processes, and digestive 

 ferments. A pseudo-moneral or cytodal stage was reached with a number 

 of chromatin-grains within the periplasm. The next stage was the 

 organization of the grains into a definite nucleus ; the cytode became a 

 protocyte, the starting-point of many complications and elaborations. 

 The chromatin-constituents of the cell are regarded as a number of 

 minute granules, each representing a primitive living individual or 

 biococcus. Another great step in evolution was the elaboration of karyo- 

 kinesis, which in tissue-formation effects the precise partition of the 

 chromatin-elements, because these determine the qualities and behaviour 

 of the cells. The author also dealt with the divergence of animal and 

 vegetable cells, and with the lines of differentiation in the Protozoa. 



Permeability of Cytoplasm of Cells.* — G. L. Kite points out that 

 the interior parts of cells are generally assumed to be freely permeable 



* Amer. Journ. Physiol., xxxvii. (1915) pp. 282-99. 



