THE PANNEL-DISCUSSION ON INSECT PHYSIOLOGY HELD 

 ON MONDAY THE 7"' SEPTEMBER 



Частная дискуссия по фи;шолог11и насекомых, которая состоялась 

 7 сентября 1959 г. 



М. V. Brian (Great Britain). (The source of the moulting hormone in ants.) I have so 

 far been imable to find the prothoracic glands in the larva of the ant Myrmica, but I had 

 found a large pericardial gland in the anterior part of the abdomen which had a mimilar 

 histological cycle. The transplantations however had failed so far to show that it is analo- 

 gous to the prothoracic glands. This is a remark to the discussion initiated by Prof, 

 de Wilde the basis of whicli was that the ability to metamorjohose remained in insects 

 which have lost their prothoracic glands and that perhaps some other gland took over 

 their function. 



A. F. O'Farrell (Australia). Accurate measurements of the volume of the corpora 

 allata and head lobes (ventral glands) have been made at frequent and carefully timed 

 intervals throughout the first instar in Blattella germanica L. as reported here by O'Far- 

 rell, Stock, Rae and Morgan. Tliere are large, rapid, systematic changes in cytoplasmic 

 volume of both these glands. The changes are related in time to recognizable features 

 of the moulting cycle, or regeneration process, or both, and the sequence is such as to 

 suggest that increase and decrease in gland vohmie may correspond respectively to phases 

 of build-up and release of hormone by the gland. Many complexities may be concealed 

 within these phases, and there is as yet no justification for predicting that a gland of a 

 particular size should or should not be' active' in the sence of producing physiologically 

 effective quantities of hormone. Change in size as distinct from any measurement made 

 at a single point in time, is the important feature here. 



During the first five days after hatching, the corpus allatum of Blattella germanica L. 

 undergoes an increase in volume tliree times as great as the total difference in volume 

 between the corpus allatum at hatching and immediately after the first ecdysis. If such 

 relatively enormous volume changes can occvir within a single instar, comparisons between 

 corpus allatum volumes in different instars are unlikely to be good indicators of changes 

 in activity during development, unless it is certain that the maximum (or minimum) 

 volumes for each instar are being compared. What is really needed may well be a complete 

 analysis of volume changes for every instar — a very laborious but not impossible task 

 which might also assist the interpretation of development by providing better markers 

 of physiological timing for various experimental procedures. 



M. Gersch (DDR). Auf die Bemerkimg von Professor de Wilde ist zunächst zu sagen, 

 dass der Begriff Neiirohormon zur Zeit leider nicht völlig einheitlich gebraucht wird. 

 Daher sei eine begriffliche Klarst elkmg vorausgeschickt. Unter Neurohormonen sind 

 die in Nervenzellen unter histophysiologisch erkennbaren Sekretionserscheinungen 

 gebildeten Substanzen hormonaler Wirkungsweise zu verstehen. Es ist daher angebracht, 

 zwischen Neurokrinie und Neurohumoralismus zu unterscheiden. 



Da die Erscheinung der Neurosekretion wohl bei allen Tierstämmen mit einem zentrali- 

 sierten Nervensystem auftritt, können die bei Insektien vorliegenden Verhältnisse m. 

 A. n. nur bei einer vergleichend -physiologischen Betrachtungsweise sinnvoll eingeordnet 



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