NEUROSECRETION 129 



of a cyclic variation in the activity of these cells. The application of 

 adrenahne to the animals is sufficient to initiate the secretory cycle, 

 and also leads to an increase in the number of cells active, but the 

 cycle does not go to completion and only very small inclusions are 

 to be found. Similarly novocaine increases the number of cells 

 actively secreting. 



Harms (1948) finds that in the cerebral, sub-oesophageal and the 

 first two ventral ganglia there are two types of secretory cell : <2-cells 

 and blue cells. Herlant-Meewis (1956, 1957) Hubl (1953, 1956), 

 Brandenberg (1956), Aros and Vigh (1959) and Marapao (1959) 

 have all found neurosecretory cells in various species of earthworms. 

 The Naididae, Lumbriculididae and Enchytraeidae all possess 

 a and blue cells (Harms, 1948). 



Herlant-Meewis (1956) describes two types of cells in the 

 cerebral ganglion of E.foetida which she labels a-cells, and ^-cells, 

 and associated with these is a third variety of ''large and medium 

 neurones". The <2-cells are found in the upper posterior regions of 

 the cerebral ganglion, and the ^-cells, fusiform in shape, and 

 present already when the animal hatches from the cocoon, are 

 found at the junction of the cerebral ganglion with the circum- 

 oesophageal commissures (Figs. 38, 39). In the sub-oesophageal 

 ganghon lies a further type of cell (w-cells). Hubl (1953) gives a 

 similar description for L. terrestris, L. rubellus,A. longa and E.foetida, 

 considering the ''large and medium neurones" of Herlant-Meewis 

 to be composed of two distinct cell populations. Later (1956) Hubl 

 noted that the ventral nervous system has its own complement of 

 neurosecretory cells; within the sub-oesophageal ganglion are the 

 M-cells of Herlant-Meewis (1956), and another type he calls the 

 c-cell which are also represented in other ventral ganglia. Aros and 

 Vigh (1958) also note that neurosecretory cells are present in the 

 sub-oesophageal ganglion and the other ventral ganglia, and that 

 these latter are organized into groups lying symmetrically on the 

 right and left sides of the nerve cord. 



Hubl (1956) believes that the c-cells may represent 6-cells in a 

 difterent stage, and Marapao (1959) describes three secretory 

 stages in one cell and further shows that the two cerebral types are 

 independent of one another. 



Production of neurosecretory hormones has often been asso- 

 ciated with cyclic bodily functions such as reproduction, pigment 



