€tJRTis.— Planaria. 
PLATE 16. 
(The figures are from camera lucida drawings of sections reduced five 
sixths in reproduction.) 
Fig. 43. The parenchyma of P. maculata showing formative cells (s) and the 
nuclei of the parenchyma proper {np). Zeiss X 2. 
Fig. 44. Portion of the cord of cells which is found lying along above either 
nerve cord from the ovaries well down into the tail, as in the stage of 
development represented by figure 54. The surrounding parenchyma 
is not shown. Zeiss X 2. 
Fig. 45. A transverse section through the atrial cavity just after it can be dis¬ 
tinguished as such (see figures 54 and 57). The surrounding paren¬ 
chyma is shown. Zeiss X 2. 
Fig. 46. A longitudinal section through one of the short cords of cells which are 
the first sign of the developing sex cells. The surrounding parenchyma 
is shown. The cord is evidently composed of formative cells. The 
reproduction of this figure has made the cytoplasm of these cells less 
distinct than was intended. Zeiss x 2. 
Fig. 47. Section through one of the short cell cords which is now sufficiently 
advanced to be distinguished as a testis. Zeiss X 2. 
Fig. 48. The same at a slightly later stage. Zeiss X 2. 
0 
