4G THE TERIODIC GROWTH OF SCALES IN GADID.E 



a part of the connective tissue of the scale pocket. As concerns H. 

 Khiatsch's explanation, it is not at all clear to me, because the development 

 of the dermis is also not clear." 11. Klaatsch says that threads arise in the 

 dermis without any participation of its cells ; hut literature seems not wholly 

 to confirm this view, as we read, " Die Fiiden aus Zellen entstehen, indem sie 

 aus dem Plasma der letzteren hervorwachsen (Kanvicr)." Ussow then proceeds 

 to note the varying opinions of difierent authorities in regard to the origin of 

 the fibrils of connective tissue, and he concludes his remarks on this subject 

 with the following sentence : — 



^^ Elne fjenauere VorsteUung von dem hisiogenetisclien Vorgange der 

 FihriUenhildiing auf Gi-und direkter Beohacldung zu gelen, ist nun freilich 

 srlvcierig tind wir sind nach wie vor auf mehr specidative Erurterungen 

 angeiniesen." 



In his preparations, Ussow sees something quite different to that described by 

 Klaatsch. According to Ussow, the first phase of development of the second 

 layer of the scale begins with a great numerical increase of the mesoderm 

 elements underlying the first layer of the scale, then a transparent inter- 

 mediate substance appears between them, firstly in a small degree, then 

 always more and more, by which process the cells now become quite sunk in 

 the intermediate substance. Ussow points out that in one of his figures 

 (6u) one sees the dermis developing, which consists of cells embedded in a 

 "round substance, and that this figure much resembles the figure showing the 

 development of the second layer of the scale. He regards it as possible, as 

 Klaatsch did, that in the development of the dermis these cells pass later 

 towards the margins of the ground substance, and that the breaking up of the 

 dermis into iilnillro does not depend on these cells. But he asks if one can 

 conclude either from his own or from Klaatsch's preparations that the fibrillro 

 originate without participation of the cells. 



He says, "Mir scheint es, man kann nur sagen, dass man die Erscheinung 

 der Schraffirung nur dann konstatiren kann, wenn die Kerne allein in dieser 

 zweiten Schicht nach unten gegangen sind (fig. 7q), aber das heisst doch 

 nicht, dass das Zerfallen in Fibrillen ohne jede Theilnahme der Zellen geschah, 

 um so mehr als wiihrend der ganzen Entwicklungszeit der Zwischensubstanz 

 dor zweiten Schicht die Zellen in diese Zwischensubstanz versenkt waren und 

 nicht an ihren inneren Eandern lagen ; das letztere scheint mir gcradczu 

 unverstandlich zu sein; diese Schicht ist so diinn, dass an welchen der inneren 

 Kiinder — den oberen oder den unteren — man auch diese zellen versetzen 

 miichte, sie doch in der Schicht der Zwischensubstanz liegen wiirden." 



He gives the following summary as to the development of the second layer 



of the scale : — 



(1) "The formation of the layer of intermediate substance precedes the for- 

 mation of the .second layer of the scale ; the intermediate substance contains 

 large nuclei embedded in it, whose plasma cannot be distinguished from the 

 intermediate substance itself; that the position of the formative cells is on 

 the inner side of the strips of intermediate substance cannot be urged, in 

 consequence of the insignificant width of that layer. 



(2) " Such a substance with large nuclei we find firstly on the floor of the 

 pocket, then beneath the first layer of the scale closely bordering on it. 



