2 9 o NATURAL SCIENCE. May, 



point forces out repetitions of the original cell in radiating directions, 

 and, by the simple mechanical result of growth, points grow into stars 

 or lines, masses grow into larger masses disposed about a centre. 

 The formation of symmetrical patterns is retarded or distorted in 

 many cases by the interference of adjoining patterns from adjoining 

 centres of symmetry, and by the limitation of growth in fixed 

 directions necessary to the production of definite organs. But in 

 any structure built up by the repetition of parts an appearance of 

 symmetry must be present. We are inclined to think that many of 

 the theories of relation between body-form and protoplasmic molecule 

 owe their origin to a neglect of the fact that pattern comes from 

 arrangement, as well as from identity, of component parts. 



Regeneration and Involution. 



From their intrinsic interest, and from their importance as 

 bearing upon problems of growth and heredity, the phenomena of the 

 regeneration of lost parts and of the degraded forms of organs are of 

 great interest. The additional attention that is now paid them may 

 be seen from the bibliography for 1894, compiled by Dietrich 

 Barfurth, and issued in the 1894 volume of Merkel and Bonnet's 

 Ergebnisse dev Anatomic und Entwickelungsgeschichte. Mr. Barfurth 

 remarks on the presence of bitterness in the disputations, and on 

 their occasional conduct with weapons unsuited to the parlour (nicht 

 immer mit salonmassigen Waffen). In the work done in 1894 u P°n 

 embryological regeneration conflicting results have been obtained. 

 In most cases, observers found that isolated cells of the two-, four-, or 

 eight-celled stages of the segmenting egg gave rise to complete embryos. 

 These results, like the original experiments of Driesch, Hertwig, and 

 Wilson, seem against the evolutionary views of Roux and Weismann. 

 If, for instance, the first division of an egg divides it into a future 

 right and left half, one would not expect a separated left half to 

 reproduce the whole. Zoja, however, working on eggs of Strongylo- 

 centrotus lividus, found that isolated blastomeres gave rise to semi- 

 morulae, although Driesch, working on an allied family, found that 

 they gave rise to complete morulae. The most important of these 

 papers is, perhaps, a critical summary of recent work by Roux, 

 published in the Archiv jilv Entwickelungsmechanik. This valuable 

 publication, we learn from the Zoological Record, may be consulted in 

 the Linnean Society's library. Barfurth himself made an important 

 series of investigations upon the regeneration of lost parts. He found, 

 in the case of the young Axolotl, that complicated wounding and 

 amputating of the limbs might result, not merely in regeneration, but 

 in regeneration accompanied by the addition of supernumerary parts. 

 The tendency to " super-regeneration " he found to be greater the 

 nearer the proximal end of the limb the amputation was made. It is, 

 so far as we know, the first case of polydactylism produced artificially. 



