ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 35 
their ducts open between the second and third pairs of legs. In Poly- 
desmidae, Julidm, and Glomeridae, the paired ovaries are inclosed in one 
sheath ; they extend to the second last segment ; anteriorly each efferent 
duct ends in a sac-shaped vulva. The testes are very like the ovaries ; 
in Polydesmidse and Julidae they are connected by transverse bridges, in 
Glomeridse the union is more complete. In Julidae each of the vasa 
deferentia is provided with a penis, but all male Diplopoda (except 
Polyxenidse) copulate by means of modified appendages — on the seventh 
segment in Polydesmidse and Julidse, on the second last segment in front 
of the anus in Glomeridae. The spermatozoa of Polydesmus, Julus and 
Glomeris are round cells, not tailed as in Chilopoda. Egg-laying occurs 
25-30 days after copulation ; the eggs are fertilized as they are laid. 
In Polydesmidse and Glomeridie the larva which leaves the egg has three 
perfectly developed pairs of limbs and rudiments of others; in Julidae 
the hatched embryo is without free appendages, and undergoes moulting 
before these appear. In Polyxenidse the newly hatched larva has only 
three well-developed pairs of limbs. After a general survey the author 
proceeds to discuss each family in detail. 
Life of Millipedes.* — Dr. O. vom Rath gives an interesting account 
of the general life of Diplopoda, discussing what the Germans call their 
Biology. He describes some common forms, Polyxenus lag urns which 
alone represents the family Polyxenidse, Atractosoma, Crasjoedosoma, and 
Chordeuma among Chordeumidse, and adds to his previous investigations 
further details about the reproductive organs and copulation of these 
forms. In regard to the nest of earth which Polydesmidse and Julidse 
form around their eggs, vom Rath believes that they simply utilize the 
nearest available material and cement it with a secretion probably from 
the anal region. The larvse pass through definite stages marked by the 
number of segments and appendages. There are six of these stages in 
the life-history of Glomeris, eight in Polyxenus , and sexual maturity in 
Polydesmidse, Julidse, and Glomeridse is not reached in the first year. 
All Diplopoda except Polyxenidse have a chitinous cuticle with 
abundant carbonate of lime ; Polyxenus is protected by its peculiar hairs ; 
the Glomeridse roll themselves up in a ball, the JulidsB, Polydesmidse, 
and Chordeumidse in a spiral ; the Glomeridse are most sluggish, next 
come the Polydesmidse, while the Polyxenidae and Julidae are much 
more active, being able to move, for instance, up the vertical glass sides 
or along the glass roof of their prison. Most are protected by their 
lurking habits and by their foramina repugnatoria or protective glands 
which give the animals a disagreeable smell and taste. In Polyxenidse 
and Chordeumidse true foramina repugnatoria are absent, but cells at 
the base of the hairs and bristles have a glandular appearance. By 
experiments vom Rath has shown how repugnant the Diplopoda are to 
hungry birds and spiders. The mid-gut is abundantly infested with 
Gregarines ; young Nematodes are also frequent ondoparasites ; and 
parasitic fungi cause much mortality. The Diplopoda are readily 
killed by drought and heat, while in winter they bury themselves, and 
are little affected by the cold. Corroborating Plateau’s experiment, vom 
Rath has shown that Julidse and Glomeridse can survive prolonged 
* Ber. Nat. Gesell. Freiburg i. B., v. (1891) pp. 161-99. 
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