Three different agglomerations of blood cells in a Caliroa limacina larva

Some time ago in our laboratory a number of larvae of Caliroa limacina Retz., the well known slug like sawfly larva of the pear, were fixed in toto and sectioned into complete series, which were coloured with EHRLICH’S or HEIDENHAIN’S haematoxylin and counterstained with eosin. Most of these larvae belonged to the last instar but one, i.e., the last instar still feeding and showing the typical mucous covering. The very last instar does not feed any more and lacks the mucous covering, showing the yellow cuticle. As in many other insects, in these larvae the blood cells during fixation agglutinate in a peculiar way. They constitute in the sections compact cell masses imitating a real tissue, but showing, in our preparations, hardly any cell boundaries. Such preparations are, therefore, almost useless for haematological purposes (cf. ROOSEBOOM, Arch. Neerl. Zool. T II, p. 432—559 (1937)). Nevertheless, we met with several striking peculiarities worth while to be recorded.