3. Die höheren Lebenseinheiten. 437 



1. Thymus de jeune Bufo vulgaris examine cinq jours apres la greife. 

 Un nombre considerable de petites cellules rondes sont en pycnose, surtout 

 au centre de l'organe, Celles de la peripherie arrivant sans doute plus facile- 

 ment ä se nourrir. A la place des fins vaisseaux que l'on trouve dans le 

 thymus normal de Bufo, ou observe ä present des trainees de cellules claires 

 ä noyau assez pauvre en chromatine, rappelant absolument les cellules myo- 

 epithelo'ides (Dustin) jeunes des Reptiles, qui se forment par gonflement et 

 multiplication amitotique des elements de la gaine perivasculaire. 



2. Thymus de Rana fusca adulte (juin) examine apres un jour de greffe. 

 Ici aussi, on observe la pycnose d'un grand nombre de petites cellules et le 

 debut de l'hypertropbie de la paroi vasculaire. Les cellules conjonctives et 

 les cellules epithelo'ides resistent aux troubles de nutrition et persistent dans 

 leur etat primitif, sans presenter de lesions cytoplasmiques ou nucleaires 

 appreciables. 



II resulte de lä: 1. que les petites cellules thymiques sont des elements 

 extremement vulnerables. L'auteur espere pouvoir etablir bientöt, que, con- 

 formement ä son opinion sur les petites cellules thymiques (d'apres ses recher- 

 ches sur les Beptiles), cette vulnerabilite les distingue des lymphocytes vrais; 

 2. que, „lorsque par le fait de la greffe, la circulation sanguine vient ä etre 

 suspendue dans le thymus, les parois de certains vaisseaux se mettent ä proli- 

 ferer et donnent naissance ä des essaims de cellules epithelo'ides"; 3. que 

 „la resistance des elements conjonctifs intrathymiques, et surtout leur ten- 

 dance ä proliferer, contraste nettement avec la grande alterabilite des lym- 

 phocytes". J. Duesberg (Liege). 



1197) Campell, D. H., The nature of graft-hybrids. 



(Amer. Naturalist 45. p. 41—53. 1911.) 

 A review of the work of Winkler, Baur and Strasburger on graft 

 hybrids or sectorial and periclinal chimeras. Gates (St. Louis). 



1198) Tanquary, M. C, Experiments on the Adoption of Lasius 

 Formica and Polyergus Queens by Colonies of Alien Species. 



(Biol. Bull. 20,5. p. 281—308. April 1911.) 

 The object of these experiments performed under the direction of Pro- 

 fessor W. M. Wheeler, was to determine whether the queens of certain species 

 of ants are parasitic upon certain other species in founding their colonies. 

 The method consisted in placing artificially dealated queens of the supposedly 

 parasitic species in a nest with a few workers and brood of the supposed host 

 species, and observing their behavior under these conditions. The experiments 

 are recorded in considerable detail. 



(1) In the case of Aphaenogaster tenneseensis and A. fulva, queens of 

 the former being placed with small colonies of the latter, out of 35 queens 

 used only one escaped destruction and was adopted by the host species; though 

 in some cases there was a tendency towards adoption as seen by the fact that 

 some of the workers licked the queen just as they would their own, while 

 others were attacking her. 



(2) Of 8 quees of Formica obscuriventris tried with workers of Formica 

 subservica, 5 were adopted by small colonies in each case. 



(3) „Altogether I tried 79 queens of L. latipes with 28 different colonies 

 of 8 different species of Lasius divided as follows: 14 colonies of L. america- 

 nus, 4 colonies of L. nearcticus, 4 colonies of L. claviger, 1 colony of L. cla- 

 viger var. subglaber, 1 colony of L. brevicornis, 2 colonies of L. interjectus, 

 1 colony of L. umbratus var. minutus, and 1 other colony of L. latipes. Out 



