No. 412.] REVIEWS OF RECENT LITERATURE. 319 
The Development of the Pupa and Fly within the Larva; The Pupa 
of Chironomus; and The Embryonic Development of Chironomus. 
To this is added a brief appendix on methods, likewise intended to 
promote the use of Chironomus as a laboratory subject. The numer- 
ous figures are well selected and useful, but in their execution 
the best of them do not rise above mediocrity. 
Incidentally there is described (on page 34) and figured the larva 
of Clinocera (Fam. Empidide), a new type of dipterous larva with 
eight pairs of prominent abdominal prolegs. LO N. 
Reactions of Protozoa. — In the Supplementband for rgoo of 
the Archiv für Anatomie und Physiologie, August Pütter! presents a 
most valuable contribution to our knowledge of the reactions of 
unicellular organisms. The fact that the reactions of these creatures 
to various stimuli are profoundly modified when the organism is in 
contact with a solid, is strikingly evident to any one that has studied 
the behavior of the Protozoa.  Pütter has subjected to a thorough 
analysis this effect of contact of solids (thigmotaxis) and its inter- 
ference with the operation of other stimuli, and the results form a 
contribution, an acquaintance with which is indispensable to all who 
wish to obtain an understanding of the behavior of these creatures. 
Exact observation of the actual movements of the organisms, close 
attention to the interrelation of structure and function, and careful 
analysis of the various factors involved, form the striking and valu- 
able features of the paper, which stands in refreshing contrast in 
this respect to some of the recent papers dealing with the reactions 
of lower organisms. The paper is so full of detail, and casts 
light on so many observed phenomena, that it is impossible to give 
an idea of the results in a brief notice. In addition to a precise 
account of the thigmotactic reaction itself, the author deals particu- 
larly with the reactions to heat and to the electric current, as 
modified by the thigmotactic reaction. The observations on electro- 
taxis are in accord, in all essentials, with those set forth by Pearl in 
the American Journal of Physiology for July, 1900, and throw some 
additional light on this subject, especially on the subject of Zrazs- 
verse electrotaxis. Attention may be further called to the fact that 
Pütter confirms for many Infusoria the method of reaction to a 
stimulus by turning toward a structurally defined side, as described 
by the reviewer. 
* Pütter, August. Studien über Thigmotaxis bei Protisten, Archiv für Anatomie 
und Physiologie, Physiologische Abteilung, Supplementband, 1900, pp. 243-302. 
