154 Mr. C. J. Gahan on the Sensory Nature of the 



we may call the pviniary process of digestion, enters into the 

 condition of the spherical globules, each surrounded hy its 

 vacuole ; and that these s])heroids, gradually decreasing in 

 size, are ultimately worked up into the so-called crystals *. 



To the further consideration of this and other questions 

 raised I intend to return at length. 



EXPLANATION OF PLATE XII. 



Fiff. 1. Amoeba after treatment with gold chloride, a, refractive body 



(? micro-nucleus). 

 Fix/. 2. Living- Amoeba, a, refractive body. 

 Fi(/. 3. Nucleus of living Amoeba, showing its relation to the refractive 



body (a) when at rest. 

 Fiffs. 4-6. Digesting matter in successive stages. 

 Fiffs. 7, 8. Homogeneous spheroids contained in vacuoles. 

 Fif/. 9. Concretionary matters in relation to the small vacuoles. 

 Fiff. 10. Relation between the spheroids and the so-called crystalline 



bodies. 



Figs. 1 and 2 drawn under Zeiss's apochromatic system, oc. 8 compeus. 

 obj. 1'4 homog. immers. Figs. 3-10 drawn under same objective, with 

 substitution of oc. 18. 



XIX. — On the prohable Sensory Nature of the "Appendix" 

 of the Antennoi of Coleopterous Larvce. By Charles J. 

 Gahan, M.A., of the British Museum (Natural History). 



Many Coleopterous larvas are provided with a remarkable 

 structure which is situated upon the distal surface of the 

 penultimate segment of the antennse. Though this structure 

 has been noticed by more than one writer on Coleopterous 

 larvge and has been described as an " appendix," an " appen- 

 dicular joint," a " blunt tubercle," and in other terms, it does 

 not seem to have attracted much attention. At least, no 

 autlior, so far as I am aware, has attempted to describe its 

 microscopical characters in detail. 



Some observations that I have recently made upon the 

 antennge of the larva of Pterostichus — a genus of Carabidas — 

 have led me to believe that the so-called appendix is in reality 

 a sensory organ. When the antennae of this larva are 

 examined under the microscope the appendix is seen as a 

 tolerably conspicuous object projecting from the oblique outer 

 (or posterior) surface of the distal extremity of tlie third 

 segment, its transverse diameter being very little less than 



* Le Uantec has shown the vacuolar fluid of several Protozoa to be 

 acid (' Annales de I'lnstitut Pasteur,' 1890, pp. 776-791). 



