ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 635 



He emphasises the necessity of assuming " reiterated species- 

 formation " (iterative Artbildung), namely, the repetition of similar 

 variations at different epochs, as if there were a " predisposition towards 

 certain lines of variability." This is a very interesting inquiry, which 

 few have pursued, as to parallelism in evolutionary processes. 



The author is not a Darwinian, but a frank Lamarckian. Not only 

 do changes in the earth and its climate bring about changes in species, 

 in part directly and in part by influencing instincts, but the instinct 

 and the will of the organisms are the most important factors in evolu- 

 tion, whether in the formation of the Ichthyosaurian paddle or in the 

 establishment of the feet of Diprotodon. But the difficulty is to 

 harmonise such psychological formulae as " will," with biological factors 

 of a more objective sort. 



b. Histology. 



Artificially induced Anomalies in Cell-Division.* — K. Werner 

 has experimented on the effects of ether spray. The cold brings about 

 proliferation and cell-lesions ; and abnormal modes of cell-division 

 ensue. Most are amitotic, but sometimes the mitotic character is pre- 

 served. The amitotic process is a traumatic, in a certain sense sim- 

 plified, mitosis. There is an unsymmetrical and incomplete rearrangement 

 of the chromatin before the metakinesis, and on this other phenomena 

 depend. Although not of equal value to mitosis, the amitosis gives 

 rise to viable cells. Giant cells of unicellular origin arise either by 

 stimulation of the centres and paralysis of the periphery (Weigert), or 

 by a hindering of cell-wall formation through the persistent activity 

 of the centres (His). 



Direct Division in Artificial Conditions.! — W. Schimkewitsch 

 directs attention to a number of experiments which he has made on the 

 eggs of Loligo and the fowl, which show that unnatural conditions of a 

 chemical nature induce direct division where indirect division should 

 occur. The variety of conditions when this occurs is great, but it 

 seems as if they might all be included in the statement that an un- 

 naturally intensified metabolism tends to induce the direct mode of 

 division. An interesting survey is taken of the numerous and very 

 varied instances where this relapse to amitosis has been observed. 



Reticular Apparatus in Spinal Ganglion Cells.J— M. Jaworowski 

 has found in the spinal ganglion cells of birds and amphibians the same 

 "reticular apparatus" as Golgi has described in mammals. It is quite 

 different from Apathy's nerve-fibrils or Holmgren's canaliculi ; it is a 

 closed structure, composed of threads, confined to the inner plasmic 

 region, and in no connection with the surface. 



Pituitary Body of Amphibians. § — A. Bochenek finds that a nerve- 

 strand from the under part of the infundibulum enters the hypophysis 

 and ends in the glandula infundibuli. In Urodela the glandula in- 

 fundibuli consists of a single segment, and is almost exclusively formed 

 of a dense meshwork of nerve-fibres. In Anura there are two segments, 



* Arch. Mikr. Anat., Ixi. (1902) pp. 85-122 (1 pi.). 



f Biol. Centralbl., xxii. (1902) pp. COo-S. 



t Bull. Acad. Interna t Bci. Cracovie, 1902. pp. 40.3-13 (1 pi.). 



§ Tom. cit., pp. 397-403 ('2 figs. ). 



