die generative Phase (Oogenese) fördert, die Photoperiode also vermuthch über die Cor- 

 pora allata als Umschalteinrichtung wirkt. 



2. Auf eine Bemerkung von Wigglesworth hin über die morphologischen Effekte 

 bei der Diapause, wird geantwortet, dass bei der Zikade EusceUs isometrische und 

 allometrische Wachstumseffekte als Folge von Tageslängenunterschieden während der 

 Larvalentwicklung ohne Diapauseprozesse auftreten; im Gegensatz zu Araschma, wo der 

 Saisondimorphismus mit Diapause gekoppelt und quasi als Sekim.därprodukt derselben 

 anzusehen ist. 



V. J. A. Novak (CSSR). (The occurence of the neurohormone С in corpora allata.) 

 To the note of Prof, de Wilde as to the character of the svibstance isolated by Prof. 

 G er sc h and his collaborators beside of different parts of the nervous system also from 

 с allata and called neurohormone C, I should remember the histological findings by 

 Nayar*) and others, of neurosecretory material, stained characteristically blue by Go- 

 mori chrome alum haematoxylin-phloxin, which occurs close to the allatic nerve inside 

 the corpvis allatiun. The recent paper by Ichikawa and Nishiitsutsuji-Uwo**) 

 has shown that the implantation of the с allatum may produce under certain circimi- 

 stanee the same effect on the activation of prothoracic glands as the activation hormone 

 from the neurosecretory brain cells. The authors ascribe this rather feeble effect to the 

 neurohormone reaching the с allata via nervus allatus. Together with what has been said 

 by Prof. Gersch, the identity of neurohormone С with the neurosecretory material 

 observed in с allatvim on one side and with the activation hormone (AH) of the пеш-о- 

 secretory brain cells (or perhaps one of its components) on the other side seems to me rather 

 probable. The effect of the neurohormone С on the prothoracic glands activation remains 

 to be shown experimentally of course. 



(The dependence between the size of с allatum and the juvenile hormone production.) 



The histological observations show that the secretory activity of the с allatum results 

 among others in an increase in volume of the gland. They are of course also other reasons 

 which lead to the increase of the gland size, as e. g. its growth or as the accumulation of 

 increte in its cells due to its hypofunction (cf. struma in vertebrates) or to reduced consump- 

 tion of the hormone by the body cells (c. f . results of ovarectomy in Calliphora, as observed 

 by E. Thomsen*). The different of these causes of volume increase are in different 

 relation to the JH production. However, all these relations taken into account, the 

 supposition seems to me to be suff iciantly based that under equal conditions, in normal, 

 healthy, well fed specimens, the size of the corpus allatum is in direct proportion to its 

 activity. The secretory activity of the gland is of course just one of the factors conditioning 

 the concentration of the hormone, another important one being the volume of the blood 

 or body respectively. 



(The identity of the JH with factor conditoning ripening of the ovaries and the 

 function of accessory glands. 



The following i-easons seem to speak in favour of this identity: 1. Through the whole 

 time of its activity since the 1st larval instar to imago the corpus allatum produces its 

 effects with equal if changing intensity on both the larval growth and the ovarian follicles 

 and accessory glands function. 2. The gland of the male has the same effect as that of the 

 female. 3. The principle of the JH activity is the same in all mentioned cases: the acti- 

 \'ation of growth and other functions of the cells which are not able to produce them in its 

 absence. 4. No signes of two different tyjDes of secretory cells or two different secretory 

 cycles have been revealed by the histological investigations. 



*) Quart. J. Micr. Sei. 97, (1) 83-88, 1956. 

 **) Biol. Bull. (M. B. L.) 116: 88-94, 1959. 



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