On the Preparation of Ultrathin Serial Sections by Means of a 



Watchmaker's Lathe 



W. NiKLOWITZ 



liistitiit fiir Mikrohiolof^ic iiiul L.xpcrinu'ntelle Theiapie, Jena, clcr Akademie cicr Wissenschaften zii Berlin 



Ultrathin sections suitablcfor studying biological 

 objects in the electron microscope arc prepared 

 by means of conventional microtomes or by making 

 use of new constructions of these instruments (for 

 references, see 16, 20). 



To-day's trend is to employ ultramicrotomcs 

 which have proved most satisfactory— such as the 

 excellent ultramicrotome of Sjostrand. However, 

 since about one year we make use of a watchmaker's 

 lathe in preparing ultrathin sections. This apparatus 

 is characterized by great simplicity both in its con- 

 struction and in its operation. I should like to try to 

 give a short description of the instrument, and to 

 report subsequently some results obtained. 



The basic principle of this ultramicrotome is a 

 commercial watchmaker's lathe, as it was used al- 

 ready by Giuntini and Edlinger (10). Technical de- 

 tails have already been reported elsewhere ( 16). This 

 ultramicrotome is fitted with a thermal advance of 

 the knife similar to that recently described (6). The 

 diflference is, that with our apparatus the cooling 

 of the metal rod supporting the knife is utilized in 

 forwarding the latter. According to the rotating 

 principle, the object to be cut passes the glass knife 

 (made of Jenaer Gerate-Glas 20) only once during 

 one cutting cycle. This ultramicrotome provides se- 

 ries of ultrathin sections that are relatively uniform 

 and have a mean thickness of about 300 A. The 

 thickness of the sections may be adjusted by means 

 of the speed with which the sections are made. In 

 the meantime several of these microtomes are put 

 into operation, and we may now state that they have 

 given the same satisfactory results. 



In order to demonstrate the usefulness and effi- 

 ciency of this microtome, some results of our in- 

 vestigations, partly still in course, partly already 

 published, shall now be reported. 



The first micrographs of ultrathin sections shown 

 were given for comparison only. They represent 

 sections of the kidney of the white mouse, an organ 

 generally chosen as an object for tests, because of 

 the variety of its submicroscopic cellular structure 

 (16). 



Regarding the problem of the origin of specific 

 granules from the milochondria in Elvlich's ascites 

 carcinoma of the white mouse, the microscopical 

 (phase contrast) and histochemical investigations 

 carried out in our institute by Kieser (12) shall be 

 extended by means of ultrathin sections. The mito- 

 chondria of the tumor cells have the same specific 

 substructure as already described for other tissues 

 (21). The cristae, however, may be arranged both in 



the longitudinal and the transverse direction of the 

 milochondria. Furthermore, there are to be seen 

 single or several spherical granules, strongly osmio- 

 philic, and enveloped by a common membrane. They 

 are, in early stages of development, of the same 

 magnitude as the mitochondria. These preliminary 

 results, therefore, may suggest that the granules 

 possibly may arise from mitochondria, as is the 

 case in the cloudy swelling of the kidneys (8). 



Recently it was shown on difTercnt objects that 

 the plastids of the higher plants are formed of sub- 

 microscopic lamellae (summarizing literature see 

 Frey-Wyssling, (7)). Systems of such lamellae are 

 demonstrable also in the chromatophores of the 

 green algae. This fact has been demonstrated by 

 means of a micrograph of a chromatophore of a 

 green algae, the mean thickness of the lamellae being 

 30 to 40 A. 



This observation led us to the investigation of the 

 substructure of rv«//(v^/nrfY/(' (blue-green algae) dur- 

 ing the past few years. In this group of organisms, 

 too, we were able to state that the chromatoplasm 

 — the region of the cell containing the assimilative 

 pigments — consists of submicroscopic systems of 

 lamellae (18, 19). Having already furnished proof in 

 a previous paper that systems of lamellae are to be 

 found in Rhodospirillum rulvum, an autotrophic 

 bacterium (17), we are now able to state definitely 

 that /// all ori^anisms containitii; chlorophyll , theassi- 

 milatory pif^ntents are probably attached to submicro- 

 scopic systems of lamellae. 



Furthermore, three types of granules may be 

 differentiated in cyanophyceae: small, strongly os- 

 miophilic granules, granules of inorganic phosphate, 

 and, as a particular and characteristic group, gran- 

 ules exhibiting lamellar structure in ultrathin sections 

 and having mitochondrial function, as was demon- 

 strated in histochemical investigations. This latter 

 group of granules was provisionally designed as 

 "ferment active granules" (4, 5). 



Among the representatives of the Nostocaccae 

 there are further distinct elements in the region of 

 the ccntroplasm. a detailed description of which will 

 be published elsewhere (19). 



For a number of years, we have also been con- 

 cerned, to a certain extent, with the substructure of 

 bacteria (13-15). The results of our recent investiga- 

 tions, comprising primarily the problem of the nu- 

 cleus and of equivalents of the nucleus respectively, 

 will be published elsewhere. According to our obser- 

 vations, the equivalents of the nucleus, both in bac- 

 teria and in cyanophyceae. as seen in electron micro- 



