PEOGRESS OF MICROSCOPICAL SOIENCB. 265 



parenchyma, the same as the epidermal layer of the author's preced- 

 ing memoir. lu a short time a third layer was devcloijed between 

 these two. When the vasciilar cylinder had undergone a considerable 

 increase in its size and in the number of its vessels, a new element 

 made its aj^pearance. An exogenous growth of vessels took place in 

 a cambium layer, which invested the pre-existing vascular cylinder. 

 The author distinguishes the latter as the vascular medullary cylinder, 

 and the former as the ligneous zone. The newly-added vessels were 

 arranged in radiating laminse, separated from each other by small but 

 very distinct medullary rays. At an earlier stage of growth traces of 

 vascular bundles proceeding from the central cylinder to the leaves had 

 been detected. These are now very clearly seen to leave the sm-face 

 of the medullary vascular cylinder where it and the ligneous zone are 

 in mutual contact ; hence tangential sections of the former exhibit no 

 traces of these bundles, but similar sections of the ligneous zone pre- 

 sent them at regular intervals and in quincimcial order. Each bundle 

 passes outwards through the ligneous zone, imbedded in a cellular 

 mass, which corresponds, alike in its origin and in its direction, with 

 the ordinary medullary rays, differing from them only in its larger 

 dimensions. At this stage of growth the plant is obviously identical 

 with the Diploxijlon of Corda, with the Anahathra of Witham, and, so 

 far as this internal axis is concerned, with the SigiUaria elegans of 

 Brongniart. 



Tlie Modes of Origin of Infusoria. — One of the best and most 

 highly suggestive papers that have for years api^eared is that which 

 Dr. Bastian, F.E.S., published in the ' Proceedings of the Eoyal 

 Society ' for April. It is so good that we envy the ' Proceedings ' the 

 possession of it. It is of considerable length, amply illustrated, and 

 deals with the subject more simply and intelligently than we have 

 seen in most of the writings on the subject. It certainly aj)pears 

 that the author is justified in the conclusions which he has drawn 

 from a vast series of observations conducted during the past few 

 years. This paper ends by stating that the phenomena which the 

 author has described as taking place in the "proligerous pellicle" 

 may be watched by all who are conversant with such methods of 

 investigation. He does not require to call in the aid of the chemist ; 

 he need exercise no special precautions ; the changes in the pellicle 

 are of such a kind that they can be readily appreciated by any skilled 

 microscopist. Just as he has supposed that living matter itself comes 

 into being by virtue of combinations and rearrangements taking place 

 amongst invisible colloidal molecules, so now does the study of the 

 changes in the "pellicle" absolutely demonstrate the fact that the 

 visible new-born units of living matter behave in the manner which 

 he has attributed to the invisible colloidal molecules. The liviug 

 units combine, they undergo molecular rearrangements, and the 

 result of such a process of heterogenetic biocrasis is the appearance 

 of larger and more complex organisms ; just as the result of the 

 combination and rearrangement between the colloidal molecules was 

 the ajipearance of primordial aggregates of living matter. Living 

 matter is formed, therefore, after a process which is essentially 



