702 MEDICAL MYCOLOGY 



spores are thus connected by hyaline isthmuses. Occasionally an isthmus may 

 be found with a remnant of the old deeply staining septum still unchanged 

 in its center. 



Besides these three, there is another group in which the septa are not to 

 be demonstrated by the ordinary stains. The protoplast appears to contract 

 at regular intervals, yielding a series of noncontiguous spores, held together 

 for a time by the connecting segments of the evacuated hyphal wall (Fig. 

 117). Drechsler believed that cross walls appear in the development of 

 sporogenous hyphae throughout the genus but are too thin to be seen in these 

 forms. 



Owing to the very small size of the cells, it is not always possible to dis- 

 tinguish nuclei from metachromatic granules. The spores germinate in dilute 

 nutrient solutions by swelling and emitting 1-4 germ tubes, the number being 

 quite characteristic for each species. 



Fig. 117. — Actinomyces Lavendulae. Portion of aerial liypha (X2,750). (After Drechsler 1919.) 



Methods for Study. — Drechsler recommends the following methods as be- 

 ing especially suitable for studying Actinomyces. The fungus is grown on 

 a suitable substratum, such as potato or glucose agar. Growth on potato agar 

 is more prompt and productive of mycelium on most species; but as its use, 

 especially with species exerting a strong tyrosinase reaction, stimulates to 

 excessive guttation and disruption of the sporophores by the extruded drop- 

 lets, a medium not possessing this property is advantageous. After the cul- 

 tures have attained the proper degree of maturity, the whole growth is cut 

 from the agar and removed from the tube as carefully as possible. A slide, 

 smeared with albumin fixative, is now brought into firm contact with the 

 mycelium and then separated, precautions being taken to avoid any sliding 

 of the two surfaces on each other. If the growth is not too young, this pro- 

 cedure will leave the upper portions of the aerial mycelium adhering to the 

 slide without serious disarrangement, and killing and fixation may be at once 

 effected by the use of strong alcohol. The material is subsequently stained 

 and mounted in balsam. The quality of preparations in which the spore chains 



