1510 Journal of Applied Microscopy 



vesicles, instead of remaining round became branched, and the secreting cells 

 became columnar, or multiplying, filled the cavity of the vesicles with round 

 cells. These changes are identical with those described as " compensatory 

 hypertrophy," but the thyroid lobes did not enlarge, on the contrary, sometimes 

 they seemed to become smaller. This would coincide with the view that the 

 parathyroids manufacture the secretion, and the thyroid stores it ; when the 

 parathyroid had been removed there would be no secretion for the thyroid to 

 store. 



In a number of dogs important histological changes followed excision of a 

 portion of the superior laryngeal and vaso-sympathetic nerves on one side, and 

 the lateral thyroid lobe on the other side. The colloid disappeared from the 

 remainder of the thyroid. Usually the secreting cells multiplied into the cavity 

 of the vesicle. In one case, the dog having survived the experiment, the lobe 

 was excised 49 days later. It was greatly enlarged and weighed 35 grams, 

 which is three or four times the normal weight. The proliferated secreting cells 

 did not fill the cavities, which contained instead a watery secretion. The great 

 size of the lobe was due to a growth of young thyroid tissue between the vesicles. 

 This shows the possibility of defective innervation being the cause of serious 

 symptoms and pathological changes. j. h. p. 



GENERAL PHYSIOLOGY. 



Raymond Pearl. 



Books and papers for review should be sent to Raymond Pearl, Zoological 

 Laboratory, University of Michigan, Ann Arbor, Mich. 



Dale, H. H. Galvanotaxis and Chemotaxis of In this work detailed comparisons 

 Ciliate Infusoria. Part I. Jour. Physiol. , . , , 



26: 291-361, 1901. were made between the chemotactic 



and electrotactic reactions of certain 

 organisms, for the purpose of determining to what extent the electric current 

 stimulates through its chemical action. The experimental work was done 

 mainly on the infusoria parasitic in the intestine of the frog. The species used 

 were : Balantidium diiode7ii, B. elo?igatuvi, B. eiitozoon, Nydothcnis cordi/ormis, 

 and Opalina ranarum. On account of the high osmotic pressure of the medium 

 in which these organisms normally live it was necessary to examine them in a 

 solution of approximately equal concentration. A .() per cent, solution of NaCl 

 was used for this purpose, the organisms being shaken directly into it from the 

 intestine. It was found that the chemical reaction of the solution in which the 

 infusoria were placed had a very marked influence on their responses, so that it 

 was necessary to conduct parallel experiments with solutions carefully made acid, 

 neutral or alkaline. The chemotaxis was tested by introducing into the solu- 

 tion containing the organisms, either on a slide or in a watch-glass, capillary 

 tubes filled with the test solutions. The principal solutions employed for test- 

 ing the chemotaxis were an organic acid (acetic or butyric), a mineral acid 

 (H.^SO^), and an alkali (NaOH or Na.^CO.,). The electrotactic experiments 

 were performed in the usual way with a stimulation trough, to which the current 



